354 NOTES. 
Note XI., Cuaprer III, p. 110. 
THE FUNCTIONS OF THE NERVOUS SYSTEM OF THE 
CRAYFISH. 
Mr. J. Ward, in his “ Observations on the Physiology of the Nervous 
System of the Crayfish,” (Proceedings of the Royal Society, 1879) has 
given an account of a number of interesting and important experiments 
on this subject, 
Note XII, Cuaprer III. p. 124, 
THE THEORY OF MOSAIC VISION. 
Oscar Schmidt (‘‘Die Form der Krystalkegel im Arthropoden Auge :” 
Zeitschrift fiir Wissenschaftliche Zoologie, XXX. 1878) has pointed out 
certain difficulties in the way of the universal application of the theory of 
mosaic vision in its present form, which are well worthy of consideration. 
I do not think, however, that the substance of the theory is affected by 
Schmidt’s objections. 
Nove XIII., Coaprer III. p. 135. 
THE SPERMATOZOA. 
Since the discovery of the spermatozoa of the crayfish in 1835-36 by 
Henle and von Siebold, the structure and development of these bodies 
have been repeatedly studied. The latest discussion of the subject is 
contained in a memoir of Dr. C. Grobben (“ Beitriige zur Kenntniss der 
miannlichen Geschlechtsorgane der Dekapoden:” Wien, 1878). There 
is no doubt that the spermatozoon consists of a flattened or hemi- 
spherical body, produced at its circumference into a greater or less 
number of long tapering curved processes (fig. 34 F). In the interior 
of this are two structures, one of which occupies the greater part 
of the body, and, when the latter lies flat, looks like a double ring. 
This may be called, for distinctness’ sake, the annulate corpuscle. The 
other is a much smaller oval corpuscle, which lies on one side of the 
first. The annulate corpuscle is dense, and strongly refracting ; the oval 
corpuscle is soit, and less sharply defined. Dr. Grobben describes the 
annulate corpuscle as “napfartig,” or cup-shaped ; closed below, open 
above, and with the upper edge turned inwards, and applied to the 
inner side of the wall of the cup. It appeared to me, on the other 
hand, that the annulate corpuscle is really a hollow ring, somewhat 
