ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 751 



regarded as doubtful by Dr. Marenzeller ; and it would seem tbat 

 though some specimens may have attained a considerable size in the 

 fifth year of transj)lantation, still a term of seven years is necessary 

 to produce a marketable and profitable article. Dr. Marenzeller also 

 mentions the fact that, besides being beautifully formed and rounded, the 

 cuttings retain these qualities, and perfect health, with increasing size. 

 In conclusion, Buccich proposes the question whether the under- 

 taking can be made profitable, and answers it in the affirmative. 

 Dr. Marenzeller concludes that the propagation of sponge by cuttings 

 is not to be recommended to people without capital, but is more 

 suited to the attention of a capitalist, or an association of capitalists, 

 and to be conducted on a large scale. 



Organism which penetrates and excavates Siliceous Sponge- 

 Spicala.* — Professor P. Martin Duncan, referring to his paper at 

 p. 557, says that since writing it he has observed siliceous sponge- 

 spicula, obtained from great depths, which are affected by an organism 

 (probably a plant, and named by the author Spongiopliagus Garteri) 

 whose cells are much larger than those he previously described, and 

 whose penetrations, therefore, are wider and much more visible. On 

 the head of a large spinulate spicule he found many circular pits, each 

 containing an organic mass without definite cell-wall, and yet granular 

 and green in colour by transmitted light. These pits are shallow, and 

 are 2 oVf ™^^ i^ diameter. Similar pits and of the same dimensions are 

 seen on other spicula ; but they are deep, and resemble cylindrical 

 tubes with hollowed-out bottoms. Some reach the axial canal, which 

 has become enlarged. The penetrations contain granular organic sub- 

 stance, and so do the enlarged axial canals. The walls of the enlarged 

 axial canals are frequently very irregularly eroded, and look " worm- 

 eaten "; the hollows are, moreover, green with the very visible granular 

 matter. It is evident that the assimilation of the organic substance in 

 the sponge-spicule by the vegetable organism produces the destruction 

 of the siliceous structure ; and probably the colloid silica unites with 

 the protoplasm of the destroyer and forms an organic compound with 

 it. Large cells and small nucleus-like cells operate, producing pene- 

 trations of corresponding diameters through the spicula down to the 

 axial canal. The vegetable growth occurs there, and the amount of 

 erosion does not appear to be in relation with the size of the primary 

 penetration. 



The organism is not an Achlya ; and all that can be said is that 

 it consists of cell-like bodies without very definite cell-walls, but 

 evidently with a very delicately limiting texture, surrounding a 

 granular greenish plasma, and that there is much free and non-cellular 

 plasma with bodies like small nuclei, the whole having a faint green 

 tint. 



Protozoa. 



Structure of Unicellular Animals in Gener^l.f — M. Ch. Eobin 

 thinks that " when considering the essential conditions for the fulfil- 



* Ann. and Mag. Nat. Hist., viii. (1881) pp. 120-2. 

 t ' Journ. Anat. Physiol.' (Kobin), xv. (1879). 



3 D 2 



