With his own contributions and from the students, he gathered important pieces, achieving the value of the collection and laying the foundations for the realization of a great museum that continues to this day.
Source:[2] Beginning in 1897, the young Brother Judulien went every Thursday to the National Museum of Natural Sciences, requesting help to classify the insects he had kept in a box shaped like a book.
Here I am in the pampas of the Argentine Republic, wanting to establish a parallel between the work of Serignan peloton beetles (where Fabre was conducting his studies) and that of his rivals in the Western Hemisphere ...[5] In 1902 Florentino Ameghino agreed, after a long wait, to the direction of the National Museum of Sciences.
In recognition of the tenacious work developed by Brèthes, he offered to take charge of the entomological section, thus becoming the first specific entomologist of the museum (previously the task was in charge of the same Carlos Berg , director of the institution)[6] Ameghino reported "... as far as insects are concerned, a few days ago the manager of the entomological section, Mr. Brèthes, took possession of his job.
Over the years, remembering those times he would write: "... Ameghino made known his" Recherches de Morphologie Phylogénétique sur les molaires supérieures des Ongulés ", a work that occupies the whole volume referred to.
The ten years that I have lived in daily contact with Florentino Ameghino, from 1902 to 1911 when he died, allowed me to appreciate the intimate depths of this great man.
His decision did not mean in any way a rupture or estrangement, the Order in which he professed did not imply the ecclesiastical vote, and Brèthes kept unchanged the principles and values that had led him to exercise the ministry.
The beginning was hard for Bréthes; he was received as a public translator, and he had to give lessons and dedicate himself to various activities ... "[11] Around 1902 he met his later wife, Leontina Rossi Belgrano, an excellent draftsman and painter.
Ángel Gallardo proposed to bring the Canadian specialist Felix D'Herelle to the country, so that he could direct the Bacteriological Section of the Entomological Institute and develop a locust parasite coccobacillus, however, the desired results were not obtained.
[13] Through his constant dedication Brèthes managed to turn the National Museum into an international center of first level, to which they sent their collections from all over the continent (and even Europe) to be systematized.
From the first years of the 20th century Brèthes had established a strong friendship with Carlos Porter , classifying the new species that he sent from the Blanco River (on the western slope of Aconcagua ).
So Bertoni called Minixi brethesi a species found by him and Bréthes corresponded with the Nortonia bertonii [14] At the end of 1920, an Australian mission arrived in Argentina with the objective of finding natural enemies of the cacti that were plagues of agriculture in New South Wales .
[15] In Bogotá, he carried out a task similar to that of Brèthes, Brother Apollinaire Marie (Nicolás Séiller) of the La Salle schools.
These and other highly favorable considerations for our scientific environment and for our country have suggested the following letter that the British Museum has addressed to the director of the entomological section of the National Museum of Natural History, Dr. Juan Brèthes, following the publication of his last work in these Annals ... "[17] In fact it was the collection of coccinellids collected by Charles Darwin on his expedition aboard the Beagle .
Contribución al estudio de los Véspidos sudamericanos y especialmente argentinos, Anales del Museo Nacional, t. IX, 1903.
Contribución preliminar para el conocimiento de los Pepsis, Anales del Museo Nacional, XVII, pág.
Description d´un nouveau genre et d´une nouvelle espèce d´Hemiptère Sud Americaine, Revista Chilena de Historia Natural, t. XVII, pág.
Quelques Ichneumonidae nouveau recueillis par M. le Prof. Porter dans les provinces d´Aconcagua et Tacna, Revista Chilena de Historia Natural, t. XVII, pág.
Description d´un nouveau genre et d´une nouvelle espèce d´Ortalidae du Chili, Anales de Zoología Aplicada, Año III, pág.
El piojo del pino Leucaspis pini, Anales de la Sociedad Rural Argentina, t. LI, pág.
El pequeño escarabajo negro, Dyscinetus gagates Burm, Anales de la Sociedad Rural Argentina, t. LI, pág.
El Pulex irritans L., parásito del cerdo, Anales de la Sociedad Rural Argentina, t. LIII, pág.
Cucilletta d'Insectes au Rio Blanco III Dipteres, Revista Chilena de Historia Natural, XXIII, pág.
Sur une collection de Coccinellides (et un Phalacoidae) du British Museum, Anales del Museo Nacional, t. XXXIII, pág.
Sur une collection de coccinellides du British Muséum, Anales del Museo Nacional, t. XXXIII, pág.
Coccinellides du British Muséum avec une nouvelle famille de coléoptères, Anales del Museo Nacional, t. XXXIII, pág.
Une nouveau Staphylins (Col.) muricole de la République Argentine, Anales del Museo Nacional, t. XXXIV, pág.
Description d'un nouveau genre et nouvelle espèce d'Ulididae du Chili, Revista Chilena de Historia Natural, XXX, pág.
Elementos de mineralogía: texto aprobado por el S.G. para los colegios nacionales y escuelas normales, Buenos Aires, Libr.
Contribution pour la connaissance des chrysomélides du Chili, Revista Chilena de Historia Natural, XXXII, pág.