320 MB. ii. r. wooDWABD OS THE [Mar. 28, 



numbering 11/12 and 13/14 ; in five specimens additional glands 

 were present on 11/12 only ; in four on 13/14 only ; while in 

 one example additional glands were present on 13/14, 14/15, 

 15/16th '. These accessory genital glands were rendered easily 

 visible on dissecting the specimens under spirit, but their real 

 nature could only be made out either by means of sections examined 

 microscopically or, more roughlj^ by isolating the gland and 

 clarifying it entire. 



One specimen was of such exceptional interest that a detailed 

 description is necessary. This was a large sexually adult A. longa, 

 possessing well-developed testes on mesenteries 9/10, 10/11, and 

 ovaries on mesentery 12/13. In addition to these glands there 

 were present, on mesenteries 11/12 and 13/14, accessory organs 

 having all the microscopic structure and detailed relationships of 

 true genital glands. The anterior and larger pair of these bodies 

 corresponded in position to the anterior pair of additional ovaries 

 described in my former paper ^, but they differed very much from 

 these both in appearance and shape, being a flattened fan-shaped 

 structure with a slightly branched extremity, resembling the normal 

 testes rather than ovaries (Plate XXIV. fig. 2). 



The additional gland of the right side when removed from the 

 body, stained and clarified entire (fig. 2 a), was seen to present the 

 following appearance : — Its main mass was composed of a great 

 number of closely-packed, small, rounded cells, imbedded in a slight 

 amount of connective tissue. 



The cells situated near the base of the gland were slightly larger 

 and more uniformly diffused than those nearer the middle and free 

 end, which latter showed a marked tendency to be aggregated into 

 masses, roughly resembling the acini of a typical gland. The 

 nuclei of the cells, when seen under a high magnification, present 

 a vei'y charactei'istic appearance, owing to the arrangement of the 

 chromatin round their periphery. This is a stage in nuclear 

 division which immediately precedes the formation of the nuclear 

 spindle. The presence of all (or nearly all) the cells in this stage 

 of division indicates that nuclear division is here extremely rapid 

 and takes place in most of the cells at the same time ; the resting- 

 stage appears to be slurred over, the nuclei emerging from one 

 division and passing straight into the early stages of the next 

 without any marked pause. 



If we compare the structure of this body with that of the testes 

 (Plate XXIV. tig. 3), we notice at once tlie very strong resemblance, 

 in the aggregation of the cells into masses, in the prevalence of this 

 particular division stage in the nuclei, and in the larger size of 

 the cells at the base as compared with those at the free end of 

 the gland. 



The only observable differences between the testis and this 



1 Three of the nine specimeas possessed of additional genital glands on the 

 11/12 mesentery had testes developed in this situation, while the remaining six 

 had ovaries. 



2 P. Z. S. 1892, p. 184, pL xiii., ov\ 



