250 



SCIENGE. 



[N. S. Vol. XI. No. 268. 



increase ia size and finally collapse, often 

 opening distinctly to the exterior. The next 

 division begins Almost immediately after 

 their collapse. The excretion of fluid during 

 maturation and fertilization, the tendency 

 to vacuolation of the protoplasm observable 

 in the polar bodies and injured eggs and the 

 accumulation of fluid in temporary inter- 

 cellular cavities during cleavage are proba- 

 bly, as Kofoid suggests concerning similar 

 phenomena in pulmonates, etc., connected 

 with life in fresh water. The cleavage is 

 spiral. 



Concerning Cotylogaster occidentalis sp. nov. 



Preliminary notice. W. S. Nicherson. 



An American representative of the trem- 

 atode genus Cotylogaster occurs in the Mis- 

 sissippi valley parasitic in the ' sheeps- 

 head.' The animal is from 8-lOi mm. 

 long. The anterior proboscis-like part of 

 the body is terminated by a five-lobed disk 

 surrounding the mouth. The ventral sur- 

 face bears a compound sucker composed of 

 from 132-144 acetabula of v?hich from 31 to 

 34 form a median longitudinal row of trans- 

 versely elongated grooves ; the remaining 

 100-110 are in a single row surrounding 

 the median series. These are rounded or 

 elliptical in outline and not definitely ar- 

 ranged with respect to the members of the 

 median row. Marginal organs are present. 



From tlie dorsal surface near the pos- 

 terior end rises a broad conical elevation. 

 The excretory pore is at the base of this 

 cone between it and the posterior margin of 

 the sucker. The genital aperture is me- 

 dian, in front of the margin of the sucker. 

 A penis is lacking : the testes are two in 

 number posterior to the ovary. The ovary 

 is smaller than the testes and on the left of 

 a median plane. The shell gland is an- 

 terior to the ovary, difl'use. The vitellaria 

 are a pair of elongated laterally placed 

 cords of tissue. The eggs are numerous, 

 spheroidal, destitute of yolk cells. When 



discharged they contain a fully formed em- 

 bryo with unforked intestine and simple 

 subterminal sucker at posterior end. The 

 body of the embryo is covered in part by a 

 simple epithelium bearing distinct tufts of 

 cilia. 

 Studies in Eartlnvorm Chlorogogue. W. J. 



EiCE. Read by title. 

 A demonstration of slides illustrating the Com- 

 pound Oosphere of Albugo bliti, as published 

 in the Botanical Gazette, September and Oc- 

 tober, 1899. F. L. Stevens. 

 The simultaneous mitoses of the oogonial 

 nuclei, the multinucleate oosphere and 

 antheridial tube, the extrusion of many 

 male nuclei into the oosphere, the fusion of 

 the male and female sexual elements in 

 pairs to form about fifty fusion nuclei as 

 well as the new cell organ, the coenoeentrum 

 were abundantly illustrated by slides. The 

 peculiar feature of this work lies in the fact 

 that while this species presents a compound 

 oosphore and a multiple fertilization, other 

 related species seem to show only a simple 

 oosphere and a simple fertilization. 

 Gametes and Gametangia of the Phycomycetes. 



B. M. Davis. Read by title. 

 Suggestions toward a classification of plant 

 societies based on topographic development. 

 H. C. CowLEs. Read by title. 



The early stages of development of ventral nerves 

 in Cyelostomes and Selachians. H. V. Neal, 

 Knox College. 



Problem — Is there a difierence in the 

 modes of development of ventral nerves in 

 the lower and the higher vertebrates? In- 

 vestigators differ in their results. Obser- 

 vations on embryos of Squalus and Petro- 

 myzon preserved and stained by the raw 

 Roth-Pyrogallic acid method have given 

 some positive results, while such methods 

 as the Golgi, Gold Chloride, Corrosive Sub- 

 limate, Palladium Chloride and others fail 

 in the early stages when the nerves are first 

 formed. The raw Roth-Pyrogallic acid 



