354 NOTES. 



Note XI., Chaptek III., p. 110. 

 THE FUNCTIONS OF THE NERYOUS SYSTEM OF THE 

 CEATFISH. 



Mr. J. Ward, in his " Observations on the Physiology of the Nervona 

 fcystem of the Crayfish," (Proceedings of the Eoyal Society, 1879) has 

 given an account of a number of interesting and important experiments 

 ou this subject. 



Note XII., Chapter 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. 



Note XIII., Chaptee 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 (" BeitrSge zur Kenntniss der 

 mannlichen 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 soft, and less sharply defined. Dr. Grrobben describes the 

 annulate corpuscle as " napfartig," oi cup-shaped ; closed below, open 

 above, and v/ith the upper edge turned inwards, and applied to the 

 inner si;le of the wall of the cup. It ap|ieared to me, on the other 

 uand, that the annulate corpuscle is really a hollow ring, somewhat 



