82 MR. J. B. CARRUTHERS ON THE CYSTOCARPS OF 



the processes of sexual fructification, yet I have noticed much 

 sthat may be interesting. 



I have observed specially one of the specimens of CallopTiyllis 

 obtusifolia, J. Agardh. In this specimen the procarps were 

 either too degenerated — not having been fertilized — or in much 



^^^^.-w— — *, ™..*« 



too late a stage of development to thoroughly observe the dif- 

 ferent stages of growth. They appear scattered without any 

 order over the whole of the upper segments. They take place 

 within the thallus between the cortical layer and the medullary 

 part. The procarps which I have observed consist of a group of 

 cells in shape like stags' horns, but broader and flatter; these 

 cells project from a common point of attachment inwards towards 

 the medullary layer and between the large cells. I could not find 

 younger states of these procarps ; and so could not ascertain the 

 normal form of the carpogonial branch. I was also not able to 

 see out of which cell of the carpogonial branch the spore- 

 bearing branches originate. The first process immediately after 

 the fertilization of the procarp is the formation of very numerous 

 small cells and short rhizoids in the tissue around the procarp ; 

 these cells are formed chiefly in the medullary part of the thallus 

 between the large centre cells, and cause a slight swelling of the 

 whole medulla at that point. At the same time there is also an 

 increase in the cells of the cortex, which is extended outwards ; 

 and so arises at the point of the fertilized procarp a lens-shaped 

 swelling of the thallus equal on both sides. 



This slight swelling of the thallus represents a fruit in a very 

 young state of development. The fruit- wall consists of a varying 

 number of cells, but is very much thicker than the cortex before 

 fertilization. The cells of the outermost layer are arranged at 

 right angles to the surface of the wall ; but tho.se nearer the 

 centre of the swelling have no apparent order, and are larger than 

 the outer cells, the innermost cells being the largest, and being 

 surrounded by smaller interstitial cells in fairly large numbers. 

 The whole fruit-wall is usually pretty compact, though not so 

 much so as in the cortex of the ordinary thallus. The young 

 fruit-nucleus — the thickened part of the medulla — now shows the 

 large cells parted asunder, and surrounded by more or less 

 compact masses of interstitial cells. This young fruit-nucleus 

 includes, on one side in the part nearest the cortex, the remains 

 of the fertilized procarp. From this procarp had begun, it would 

 appear, the increase of the interstitial cells of the nucleus ; also 



