60 SUMMARY OF CURRENT RESEARCHES RELATING TO 



masses of cells. Under other conditions reticulum and a corresponding 

 membrane-growth apparently also take their origin from limb-bud 

 mesenchyme. In one sectioned live-day culture Congdon saw the • 

 contents of the wall of the atrial canal moving out into a strand of 

 very coarse reticular growth, such as is common in cultures from four-day 

 ventricle. Primitive myocardium of four- or five-day heart, therefore, 

 apparently grows out as a coarse mesh, but it is unlikely that heart- 

 muscle of the older ventricle lias this power. 



A growth of polyhedral cells resembling those from sub-pericardial 

 reticiilum was traced in sections to the endocardial cushion of the ven- 

 tricle (thirteen-day). The scleretogenous tissue of a limb-bud can move 

 out into the plasma for a short distance, but has little vitality (seven- 

 day). There is an extension of the ectoderm of a limb-lnid out into the 

 plasma, but this is due, in part at least, to a creeping of the original 

 layer, as is shown by its marked thinning on the surface of the limb-bud 

 (five- and ten-day). The spindle-shaped pre-muscle cells of seven-day 

 limb-buds give a characteristic linear growth in the plasma and upon 

 the cover-slip. 



Nuclei of Auditory Cells in Rabbit.* — E. Vasticar describes a 

 peculiar nuclear structure in the external auditory cells and the cells of 

 Deiters in the rabbit. He has observed a similar appearance in the 

 internal auditory cells. In the external auditory cells there is a sort of 

 rodlet implanted in the cephalic pole of the nucleus and inclined towards 

 the axis of the cochlea. It is cylindrical, about a tenth of the diameter 

 of the nucleus, and up to a sixth of its length. It is formed of an 

 amorphous, opaque, non-granular substance, and its free end is in direct 

 relation with the base of the endoplasmic cone which covers the greater 

 part of the " cephalic hemisphere " of the nucleus. 



In the cells of Deiters there is a similar rodlet in a similar position, 

 but inclined away from the axis of the cochlea. Its free end is in direct 

 relation with the basal portion of the granular portion of the cell of 

 Deiters. In the cells of Deiters of the third row there is a nuclear 

 structure different from that in the first two rows. It is cylindro- 

 conical and larger. Its free end is in contact with the inferior part of 

 the granular segment, which is strongly developed. 



Structure of Erythrocytes. f — Charles D. Cupp has investigated 

 the minute structure of the erythrocytes in the " blind eel " {AynpMuma 

 means), which has the largest known red blood corpuscles), in the 

 alligator, in a snake, and in Mammals (guinea-pig and man). His 

 chief method was the study of sections. The erythi'ocyte is an extremely 

 differentiated element, especially in Mammals. It normally possesses a 

 framework in the form of a fine- threaded, somewhat elastic reticulum, in 

 the meshes of which the haemoglobin is supported so intimately that its 

 content partakes of the physical characters of gelatin. In the nucleated 

 forms this reticulum is continuous into the nucleus, supporting its struc- 

 tures. The corpuscle has a peripheral membrane or capsule into which 

 the threads of the reticulum grade, and which is derived from and 



* Comptes Rendus, clxi. (1915) pp. 58-60 (3 figs.), 

 t Anat. Record, ix. (1915) pp. 259-80 (4 figs.). 



