NOTE ON MIHAKOWICS' NEW METHOD OF IMBEDDING. 327 



the blastopore marked or in figure 9 corresponds -with the 

 position of the permanent mouthy but before the widening of 

 the permanent pharynx is formed it becomes exceedingly 

 small^ and I do not feel sure as to whether it closes up 

 entirely as I previously maintained or whether it remains 

 throughout (as LerebouUet believed), being at one period an 

 exceedingly small aperture. In any case we cannot say that 

 there is a direct conversion of the blastopore into the mouth, 

 but rather a coincidence of the stomodseal invagination 

 (invagination to form the Vorderdarm) with one end of the 

 elongated blastopore. The middle third of the blastopore 

 corresponds strangely enough with the position subsequently 

 occupied by the foot. 



The proctodseum or anal invagination does not occur till 

 very late in Limnaeus. The rectal peduncle is blind as in 

 Pisidium and Cyclas; it must not be confounded with the 

 Hinterdarm or Proctodscum^ but is a part of the Urdarm or 

 Archenteron. 



Note on Mihakowics' New Method of Imbedding. By 

 H. N. MosELEY, M.A. Oxon., Naturalist on H.M.S. 

 Challenger. 



In a late number of the ' Archiv fiir Mikroskopische 

 Anatomic ' (II Bd., 3es Hft.^ p. 586) a new method of imbed- 

 ding animal tissues for the purpose of preparing fine sections 

 of them is described by Mihakowics, who used the method 

 for the investigation of the vertebrate embryos. I have 

 employed Mihakowics^ method, with some very slight modi- 

 fications, in the preparation of sections of decalcified corals, 

 especially the Stylasteridae, with great success. In all 

 methods hitherto employed the imbedding substance has 

 had to be removed by solutions from the interstices of the 

 section of tissue before the section could be mounted and 

 rendered transparent for examination. In the present 

 method a substance is used which does not require removal, 

 but is maintained in situ without diminishing the trans- 

 parency of the object. The substance holds the delicate 

 parts together, and maintains them in their relative posi- 

 tions in the section, whereas in methods where soap, &c., 

 are used, the parts separated by section swim away most 



