192 PROCEEDINGS OF SOCIETIES. 



projections. The segmentation was sometimes not complete till 

 after eight days. These statements are in accordance with those 

 of the earlier observers, but not with those of Strieker, who 

 stated that the " cross " was never seen earlier than forty-eight 

 hours after impregnation, and that segmentation was finished earlier 

 than Klein believed. The further developments of the embryo 

 up to the twenty-second day were described. The most important 

 point discovered was the mode of growth of the chorda dorsalis 

 and central nervous system, in which the trout appears to form an 

 exception to other vertebrata. In others, as is well known, two 

 folds grow from the second or nervous layer, which, by their 

 approximation and union, form the nervous canal. In the trout, 

 on the other hand, one solid process grows out from the ner- 

 vous layer, having the chorda dorsalis beneath it. This process 

 has two projections, corresponding to the JamincB dorsales of other 

 vertebrata. The central canal does not, however, appear as an 

 open groove {or J'urcJiunffs-S2)aI fe) , but as a split in this solid pro- 

 cess. This takes place from the seventeenth to the nineteenth day. 



Dr. Klein read a second paper, on " The Nerves of the Cornea." 

 The observations described in this paper were, in the main, the 

 same as already published in the ' Quarterly Microscopical 

 Journal,' but were made by a method which, colouring the nerves 

 only, not the surrounding tissues, enables the structure to be 

 made out with a magnifying power of 250 to 300 diameters. 



Dr. Klein further replied to some of the statements and criti- 

 cisms of Dr. Lionel Beale, contained in his articles in the 

 ' Monthly Microscopical Journal ' for January and February of 

 this year. Dr. Beale was, he thought, not justified in claiming 

 for himself the discovery of networks of pale or non-medullated 

 nerve-fibres ; nor that the networks which he had described were 

 now, though long questioned, accepted by German histologists. 

 The original discovery of networks of pale terminal nerve-fibres 

 belonged to Eemak, who observed them surrounding striated 

 muscular fibres. The results of Remak were confirmed by 

 Schaflfhausen, in regard to the skin and mucous membrane. Kol- 

 liker (in 1856) made similar observations in respect to the 

 mammae ; and Axmann, in the skin of the frog; as did also Meiss- 

 ner (1857), in the submucous tissue of the intestine, and Bill- 

 roth (1858), in certain parts of the intestinal tract. With 

 respect to the cornea, a terminal network was described by 

 Arnold in 1860, the same year in which were published Dr. 

 Beale^s observations on the distribution of nerve to striped mus- 

 cles ; and, also, a network of pale fibres had been observed on the 

 capillary blood-vessels by Klebs, before the publication of Dr. 

 Beale's papers in the ' Philosophical Transactions ' for 1863-65. 



Beale had, undoubtedly, done much to advance the doctrine of 

 terminal networks ; but he had failed to see the finest termina- 

 tions, such as the minute fibres which Hoyer, Cohnheim, Kol- 

 liker, and Engelmann, had seen among the epithelial cells of the 

 cornea, starting from the sub-epithelial plexus. These were 



