Maech 21, 1902.] 



SCIENCE. 



467 



ZOOLOGICAL CLUB, UNWERSITY OF CHICAGO. 

 MEETING OF NOV. 20, 1901. 



'Experiments in Grafting Hydra': Mary 

 Hefferan. 



These experiments were carried on during 

 the year 1900 at the University of Chicago, 

 and were based upon the similar work of Rand 

 (1899) and Miss Peebles (1900). A compari- 

 son of the behavior of lateral grafts in the two 

 species Hydra fusca and Hydra viridis showed 

 a marked difference in the process of regula- 

 tion. In the former, the graft moved up the 

 stock until the head ends of stock and graft 

 were of the same length, forming a Y-shaped 

 figure. Then the two trunks gradually fused 

 into one. A graft inserted very low down on 

 the stock, i. e., in the aboral 1/5, might con- 

 strict off from the foot. In Hydra viridis the 

 process was quite the contrary. The graft 

 moved down the stock instead of up, and final- 

 ly separated from it at the foot instead of 

 fusing as in Hydra fusca. The difference in 

 size of the two species and the action of cap- 

 illarity is suggested as an explanation of 

 these different processes. In tangent grafts 

 fusion took place the more readily as the area 

 of union was increased in grafting. When 

 poles were reversed separation took place if the 

 area of union was so large that the polyps 

 were unable to twist around in order that fu- 

 sion could follow with poles in the same direc- 

 tion. It was impossible to build up Hydra of 

 abnormal length by grafting several polyps 

 together end to end. Normal form was re- 

 gained usually by constriction and separation 

 at the point of grafting, or when the com- 

 pound was not much more than the ordinary 

 length, by gradual reduction through absorp- 

 tion. In a few cases buds formed on such 

 compounds soon after grafting. These buds 

 arose entirely out of the budding region of 

 the individual components, but within what 

 would be the budding zone of the whole. The 

 general results may be summed up in the words 

 of Wetzel, '95: 'TJeberall zeigt sich ein deut- 

 liches Streben, die normal Gestalt wieder her- 

 zustellen.' 



MEETING of DEC. 4, 1901. 



'Some Observations upon the Eye of Bdel- 

 lostoma StovW : B. M. Allen. 



The eyes of this Pacific coast myxinoid show 

 a very primitive structure, which is in 

 reality the result of a complex process of 

 degeneration. The eyeball is found im- 

 bedded in a mass of fat about three times 

 its size. In one case, the eye was found to 

 lie some distance beneath the outer surface of 

 the mass of fat. Normally, however, "the cor- 

 neal surface lies on a level with the surface 

 of the fat and is often flattened to form a 

 rather extensive free surface. No eye muscles 

 nor traces of such were discovered. No oculo- 

 motor nerves were found. No traces of them 

 are discoverable in embryonic life (Kupffer). 

 There is no trace of a crystalline lens. Ac- 

 cording to G. 0. Price and Kupffer, a rudiment 

 of a lens occurs at a very early stage of em- 

 bryonic life, but very soon disappears. The 

 choroid and sclerotic coats are represented by 

 a very thin layer of unpigmented, non-vascular 

 connective tissue without any appreciable dis- 

 tinction between corneal and sclerotic portions. 

 The retina remains in the early condition of 

 an optic cup, the outer layer (pigment layer) 

 not being fused with the remaining layers. 

 All specimens showed the layer in question to 

 be widely separated from the bulk of the retina. 

 This pigment layer is composed of a single 

 layer of cubical cells devoid of pigment as far 

 as I could ascertain. A layer coiTesponding 

 to that of the rods and cones in higher verte- 

 brates is clearly present. The nuclei of these 

 structures (outer nuclear layer) are strikingly 

 well developed and regularly arranged. Cer- 

 tain characteristic cells of the inner nuclear 

 layer could be readily made out. It is impos- 

 sible at present to give an accurate account of 

 the minute histological details of this or of 

 any other part of the retina, owing to the 

 lack of living material. The ganglionic 

 layer is represented by cells scattered irregu- 

 larly throughout the inner reticular layer. 

 Fibers from these last named cells can be 

 traced in a more or less direct course to the 

 optic nerve. The outer rim of the optic cup is 

 in many cases differentiated in such a manner 

 as to suggest a rudimentary iris. A structure 

 unmistakably like an iris was found in one 

 specimen examined. The cellular structure of 

 this rudimentary iris is almost identical with . 



