Mat 10, 1907] 



SCIENCE 



731 



Origim of the Sperm-center in the Fertili- 

 zation of Cerebratulvs lacteus: Naohide 

 Yatsu, Columbia University. 

 Since the discovery that a cytaster with 

 a centriole may be formed de novo, the 

 question has been raised as to whether the 

 sperm-center may not be a cytaster pro- 

 duced by a stimulus exerted by the 

 spermatozoon. This idea has led to the 

 formulation of the chemical 'theory' of 

 fertilization. It has, therefore, become im- 

 portant to examine the origin of the sperm- 

 center. In studying the spermatozoon of 

 Cerebratiilus lacteus a definite granule was 

 found in the middle piece, which takes a 

 strong hEematoxylin stain. After the en- 

 trance of the spermatozoon into the egg the 

 middle piece swells up into a vesicle, and 

 faint rays appear centering in the granule 

 in the middle piece. The granule or cen- 

 triole then escapes from the vesicle and 

 becomes the center of the growing aster. 

 At this moment there is no centroplasm or 

 eentrosome around it, the rays reaching 

 the central granule. Later the central ends 

 of the rays become obscure and the centro- 

 plasm is accumulated around the centriole. 

 Then the centriole in the eentrosome di- 

 vides into two. But the daughter een- 

 trioles soon lose their eentrosome and be- 

 come naked. From this observation three 

 conclusions may be drawn : 



1. The centriole is actually introduced 

 into the egg by the spermatozoon, exclu- 

 ding the possibility that the centriole in the 

 sperm-aster arises from the egg. 



2. The eentrosome is derived from the 

 egg stibstance. 



3. The eentrosome is not a permanent 

 organ of the cell as has been thought by 

 some cytologists. 



A Graphic Method of Correlating Pish 

 Environment and Distribution: Albert 

 H. Weight, Cornell University. 

 It is some vears since ornithologists saw 



the advantages of some graphic means of 

 representing complex bird waves and their 

 coincident relation to physical conditions. 

 In ichthyology, a schematic method where- 

 by fish distribution and environment can 

 be correlated would seem of material aid. 



The study of a stream and its fishes in- 

 volves the consideration of factors so 

 numerous and so diverse and accumulates 

 such a mass of data, that one is almost 

 driven, perforce, to adopt some graphic 

 method to make results appear quickly and 

 clearly. 



The chart described, presents the range 

 of each species in the stream and the im- 

 portant physical conditions which obtain, 

 namely: the nature and the configuration 

 of the bottom; the depth at any given 

 point; the surface of the water; the drop 

 in the stream and the current conditions; 

 the altitudes of the mouth, source and all 

 intermediate points ; the distances in miles ; 

 woodlands, swamps, falls, mill-ponds, dams 

 in use and remains of dams, small and 

 important tributaries and whether from 

 the right or left side, bridges for land- 

 marks, canals, stream across the divide, the 

 width at any place, at every mile point 

 valley cross-sections in which the geologic 

 formations may be shown, etc. 



Venation of the Wings of Paleozoic 

 Dragon-flies: E. H. Sellaeds, Univer- 

 sity of Florida. 



The paper relates specifically to the 

 dragon-flies of the Permian and is a sum- 

 mary of results published in detail else- 

 where. The structural characters of espe- 

 cial interest are found in the disposition of 

 the veins of the radio-median area, and 

 particularly in the position of the radial 

 sector, which is observed in the case of a 

 large and well preserved specimen, to cross 

 the first two branches of the media as in 

 the case of modern dragon-flies. The 

 other main veins of this area are also in 



