228 



SUPPLE MENTAEY NOTE. 



STRUCTURE OF CORDYLOPHOKA. 



Since the earlier part of the present ^Monograph was printed there lias appeared a valuable 

 Memoir by Dr. Schulze, of Rostock, on Cordylophora lacustris {' Ueber den Bau und die Entwicklung 

 von Cordylophora lacuslris nebst Bomerkungen Uber Vorkommen und Lebensweise dieses Thieres/ 

 von Dr. Franz Eilhard Schulze, Leipzig, 1871). 



Dr. Schulze obtained the Cordijlophora in brackish water near Rostock, and has made its minute 

 structure the subject of a laborious aud exhaustive examination. By the aid of osmic acid, and 

 steeping in Miiller's .solution and in iodized serum, he has succeeded in making sections eminently 

 fitted for examination under high powers of the microscope. 



Perhaps the most important puint contained in the Memoir is his demonstration of a structure- 

 less hyaline membrane which lies between the ectoderm and the endoderm, and which, in those parts 

 where a muscular layer exists, is found on the inner or endodermal side of this layer. It is the 

 supporting lamina, " Stiitzlamelle" of Reichert, who recognised its presence in the same position in other 

 hydroids, though he confounded with it the muscular layer whose existence in the Hydroida he denies. 



Though I have had no opportunity of verifying by new examinations the results at which 

 Dr. Schulze has arrived, I am quite ready to accept his confirmation of the presence of the " Stiitz- 

 lamelle'' of Reichert. I have been long aware of the appearance of a very narrow clear space between 

 the etidoderm and ectoderm, as visible in various sectional views of hydroids (see especially PI. IV, 

 fig. 3; PI. VII, fig. G ; PI. XXIII, fig. 9 ; and woodcut, fig. 48, p. 12, of the present work) ; but I 

 could never convince myself that this appearance ought to be regarded as the expression of an inde- 

 pendent membrane. Schulze's very careful investigation, however, appears to me now to set this 

 question pretty nearly at rest, and to justify us iu regarding the " Stiitzlamelle" as a second element 

 lying between ectoderm and endoderm, the muscular layer being the other. 



Schulze informs us of an internal annular process of the "Stiitzlamelle," which runs transversely 

 across the base of the tentacle iu Cordylophora, forming a septum with a central aperture. I have 

 not seen anything of this kind. 



He can in no case find either in Cordylophora or in Hydra the secondary cells which I have 

 described as existing in the interior of the large endodermal cells of the somatic cavity, and to which 

 I believe myself justified in attributing a secreting function. Notwithstanding, however, the trust- 

 worthy means of observation adopted by Schulze, 1 am not prepared to relinquish my belief in the 

 reality of these cells. It is not impossible that their existence may depend on certain states of 

 nutrition, and that they may be present at one time and absent at another. 



The author is inclined to regard the free surface of the endodermal cells as destitute of membrane, 

 and believes that the protoplasm which is accumulated at this spot has its surface freely exposed to the 

 somatic cavity — an important and interesting fact if confirmed by subsequent observations. He has 

 also succeeded in clearly making out the presence of vibratile cilia over the whole of the endoderm of 

 the somatic cavity, not only in Cordylophora, but in Hydra, each of the cells carrying a single long 

 fine cilium on its free surface. Hydra, therefore, affords no exception to the ciliated condition of the 

 endoderm. 



The occurrence of longitudinal rugae which I have described in the endoderm of the stomach in 

 Cordylophora and Hydra is attributed by Schulze to the mere contraction of the walls. There is 

 no doubt that the distinctness of these rugre depends to a certain extent on the state of contraction of 

 the hydranth, but their existence is not on that account the less real. la many marine hydroids the 

 endoderm of the gastric walls presents well-marked lobes and rugse. 



The author maintains the ectodernud origin of the generative elements. In this I cannot agree 

 with him. I believe, on the other hand, that I have satisfactory evidence that they are products of 

 the endoderm (see above, p. 148). Schulze, it is true, affirms the existence of a continuation of the 

 hyaline " Stiitzlamelle" over the spadix, so that the generative elements would be thus separated from 

 the endoderm of the gonophore. If this be the case it would go far to prove the view taken by 



