74 ^V. .]. J)AK1X. 



rigidity to the lens, and if the former were accommodation 

 muscles one would expect a more definite and efficient 

 arrangement. The same red-staining fibres can be traced, 

 however, down the sides of the optic vesicle in the connec- 

 tive tissue, and those present between the lens and cornea 

 may be simply for the purpose of tying the lens to the sub- 

 corneal layer. Before leaving the lens it will be advisable to 

 refer to another condition seen in some of the lens-cells. 

 This is a peculiar condition of the nucleus (perhaps patho- 

 logical) observed in one or two cells in preparations fixed in 

 von Kath's fluid and also in Hermann-sublimate mixture 

 (preparations stained with Heidenhain's iron hjematoxylin). 

 The latter specimen was an eye from a small 1*. opercularis 

 or P. varius. The nucleus (PL 7, fig. (5, a,nuc.) is perfectly 

 spherical and much larger than the normal ones. The size of 

 the normal nuclei was 5*J3 /u by 4 /z (they are oval in shape), 

 whereas the s])herical ones attained a diameter of 10'6/u. 

 These nuclei were homogeneous, not staining deep black as 

 the normal ones, but rather grey, slightly darker than the 

 cytoplasm. A very delicate nuclear membrane appeared to 

 be present with the remains of deeply stained chromatin 

 substance attached to it. The cells containing these nuclei 

 do not look distorted nor vacuolated hf fixatives and the 

 nucleus appeal's perfectly natural ; no other stages could be 

 found connecting' these with the normal nuclei. 



o 



The Retika. 



The retina, being the recipient region of the eye, is of great 

 interest, and this is increased by the wonderful complexity 

 for an invertebrate and by the numerous conflicting views 

 that have been published as to its histological structure. 



I aofree with Rawitz when he said that to Patten must be 

 given the credit of solving* much of this structure. He was 

 the first to reduce chaos to order, and though he was unfor- 

 tunately carried a little too far by his imagination, he 

 published a very creditable work, especially since very little 



