526 GILBERT 0. BOURNE. 



thus. The results obtained were so nearly the same in all that 

 I will not give details of all the species examined ; to do so 

 would involve a wearisome repetition. 



In a previous paper (2) I described the calicoblasts of Muss a 

 distans as being, in the regions of most active coral growth, 

 long, narrow, and columnar, but elsewhere rounded or poly- 

 gonal, with nuclei which stain faintly in borax carmine. At the 

 same time I described structures which I identified with the 

 striated calicoblasts of von Heider, but now with the desmo- 

 cytes of Heliopdra, 



As it was very difficult to get good preparations of calicoblasts 

 from decalcified specimens of Mussa, and as they could scarcely 

 be studied in sections of hard and soft parts together, I had 

 recourse to the following method : — Thick sections of hard 

 and soft parts together were prepared in the usual manner by 

 grinding. After examination of these sections by low powers 

 suitable parts were cut out and the balsam was dissolved out by 

 xylol. They were then placed in a very dilute solution of 

 acetic acid, and the soft tissues were carefully removed as soon 

 as decalcification had proceeded far enough to loosen their hold 

 on the corallum. The tissues thus separated were either 

 arranged as flat preparations, or were again embedded in paraffin 

 and cut into very thin sections. For staining I used picro-car- 

 mine and nigrosin, or iron hsematoxylin and acid fuchsin. 



Fig. 27 is a drawing of part of a transverse section made as 

 above. Sep. and Dissep. mark the positions occupied by a 

 septum and a dissepiment respectively. Mes. are mesenteries. 

 The calicoblasts {ca.) are seen to be tall vacuolated columnar 

 cells, with distinct nuclei. At the places where the mesen- 

 teries join on to the tissues investing the corallum are seen 

 groups of structures marked dc. They are the striated calico- 

 blasts of von Heider and Mrs. Gordon. As I have no doubt 

 of their homology with similar structures in Heliopora, I shall 

 call them desmocytes. This section is characteristic in so far 

 as the position of the desmocytes is concerned. They are 

 always grouped in the greatest numbers about the insertions of 

 the mesenteries, a fact which has already been recorded by von 



