530 



SCIENCE. 



[N. S. Vol. XVII. No. 431. 



eight days of improved surroundings, the 

 relation between width and length changed 

 from fifty-three per cent, to sixty-six per 

 cent., the width of normal oysters of the 

 same age being seventy-nine per cent, of 

 the length. 



A third experiment, to find the limits to 

 the recuperative power, revealed the fact 

 that young oysters take advantage of im- 

 proved conditions more rapidly than old 

 ones. The youngest oysters in this experi- 

 ment changed in sixty days in the relation 

 of width to length from fifty per cent, to 

 sixty-eight per cent., whereas the oldest 

 changed only from forty-one per cent, to 

 forty-seven. The recuperative power of 

 the younger ones was three times that of 

 their seniors. 



These experiments show that crowding 

 alone explains the elongation; that young 

 elongated oysters can with profit be trans- 

 planted to artificial beds, where, under 

 favorable conditions, they can grow to a 

 jiormal maturity and become marketable. 



These experiments were conducted by 

 the North Carolina Geological Survey in 

 cooperation with the U. S. Fish Commis- 

 sion Laboratory at Beaufort. 



Growth of Lamprey Embryos in Nature: 

 S. H. Gage, Cornell University. (Read 

 by title.) 



Some Points in the Life History of the 

 Human Warhle Fly: H. B. Ward, Uni- 

 versity of Nebraska. 



Movements of the Cerebrospinal Fluid in 



Cryptobranchus : J. B. Johnston", West 



Virginia University. 



The eerebro-spinal fluid of Cryptobran- 

 chus normally contains a considerable num- 

 ber of red blood corpuscles which serve as 

 a convenient means of demonstrating the 

 course of flow of the fluid when the brain 

 ventricles are opened, the animal being 

 under the influence of chloretone. 



There is a general current which flows 



backward on the floor and the lower part 

 of the side walls of the brain, and forward 

 along the roof and the upper part of the 

 side walls. Subordinate circuits, each 

 more or less complete in itself, are present 

 in the hind-brain, in the mid- and 'tween- 

 brains and in the fore-brain. This is espe- 

 cially noticeable in the mid- and 'tween- 

 brains, where there is a distinct whirlpool 

 of corpuscles on the lateral wall. Also on 

 the side wall of the medulla oblongata are 

 several small whirlpools between the iipper 

 and lower currents of the main circuit. In 

 the lobi inferiores the directions of the 

 main circuit are reversed, so that the cur- 

 rent flows backward on the roof of the 

 lobes and saccus vasculosus and forward 

 on the floor. It is possible that the three 

 sections of the current are related in some 

 way to the three vascular plexuses of the 

 brain, but it is more probable that they 

 are due to the two chief isthmuses by 

 which the ventricles are divided into three 

 parts. 



The corpuscles have the appearance of 

 being driven by cilia. The fact that the 

 current is kept up after the brain is 

 opened, and that the corpuscles are driven 

 against the force of gravity when the brain 

 is tilted, and the formation of whirlpools 

 are scarcely to be explained in any other 

 way. No such long flagella as are seen in 

 the brain of Acipeiiser, nor any special 

 ciliated tracts such as have been described 

 for other forms, have been found, but ap- 

 parently the whole floor and part of the 

 side walls of the brain ventricles are cov- 

 ered with very fine cilia. 



On the Negative and Positive Phototropism 

 of the Earthworm Allolobophora foetida 

 (Sav.) as Determined by Light of Dif- 

 ferent Intensities: G. P. Adams. (Pre- 

 sented by G. H. Park:er. ) 

 Allolobophora foetida is negatively pho- 



totropic toward light from electric incan- 



