Jan., 1906.] Occurrence of Sex Organs in Aelosoma. 
435 
method of treatment and philosophy, geography in its higher 
phases is a university subject. Universities in France, Germany, 
Austria and to some extent in other countries, have prepared for 
the study of geography in their courses. Two or three Amer- 
ican universities give some systematic instruction in advanced 
geography. Many more should and, I trust, will, if for no other 
reason than the utilitarian, the preparation of teachers for 
elementary and secondary schools and the equipment of men 
for business, diplomatic, and government positions where a 
knowledge of the principles of geography is of inestimable value. 
To sum up, then, physiography and geography are two dis- 
tinct sciences. They each contribute to the full appreciation of 
the other; especially does the former minister to the latter. They 
often deal with the same basal materials, but not in the same way 
nor to the same end. Physiography describes and classifies 
physiographic features and discusses the processes and agencies 
by which they are made. Geography shows the relations exist- 
ing between man and his physical environment and classifies 
the influences and responses. Both physiography and geogra- 
phy are large, complex, and, as yet, not fully developed sciences, 
and therefore present to the investigator many unsolved and 
difficult problems. 
A NOTE ON THE OCCURRENCE OF SEX ORGANS IN 
AELOSOMA.' 
J.\s. A. Xelsox. Ph. D. 
The genus Aelosoma, representing the family Aphanoneura, 
and containing the most primitive members of the oligochaetous 
annelids, is remarkable, among other things, in that sexual 
reproduction occurs very rarely, the asexual method being the 
usual one. The latter consists in a process of fission or budding, 
by which the young individual is constricted off from the pos- 
terior portion of the parent, this process often taking place so 
rapidly that chains of individuals are formed, representing three 
or more generations. This process is continuous during the life 
of the individual, and probably amply suffices, as far as numbers 
are concerned, to insure the maintenance of the species. Sexual 
reproduction does, however, step in occasionally, and has been 
described by U’Ddekem in 1862,- and more recently by Stoic" 
and Maggi.^ According to these authors a testis is found in the 
fifth segment, (counting the prostomium as the first) ; an ovary 
1 Contributed from the Laboratory of Entomology and General Invertebrate Zoology 
of Cornell University. 
2 Bull. Acad. Sci. Roy. Belg. XII. 
3 SB. Bohm. Gesc. 1889. 
4 Soc. Ital. Nat. Sci. I. 
