90 



The Naturalist. 



and give rise to a larger mass of protoplasm, termed " Plasmodium,** 

 which has most of the characters of the individuals of which it is com- 

 posed, differing from them chiefly in size. Subseq^uently the plasmodia 

 themselves conjugate in a wholesale sort of way, and growing by the 

 absorption of fresh nutriment, the substratum becomes covered with an 

 amorphous mass of richly granular protoplasm, whose appearance is 

 remarkably characteristic. Ultimately, by a species of contraction or 

 condensation of the protoplasm round certain points, the mass becomes 

 broken up into a number of naare or less distinct portions, which take 

 on the form of the mature sporangia. At first each of these portions of 

 protoplasm is homogeneous throughout, but in a very short time the 

 surface becomes ^differentiated into a kind of structureless membrane, 

 while the interior passes over without the intermediate formation of any 

 cellular structure, into spores and capillitium. The whole now forms a 

 perfect sporangium (Fig. 1, Plate II). 



Thus the cycle of phenomena which in the aggregate make up the life- 

 history of one of these remarkable organisms returns into itself, and so 

 long as the conditions are favourable, may be indefinitely repeated. 

 That the process we have described as " conjugation should be regarded 

 -as a sexual mode of reproduction, may appear at first sight an unwar- 

 srantable use, or indeed an abuse of the terms employed ; we believe, 

 nevertheless, that if due allowance be made for the many abnormalities 

 exhibited by these plants, and the phenomena under consideration be 

 compared with what occurs in other zygosporese, the interpretation put 

 ■upon them will hardly be regarded as either strained or unnatural. 

 (To he continued.) 



Sljort '^Gim aitb #nmes. 



MoLLusoA OF Neighbourhood of Hull. — I can add one or two species 

 !to those in Mr. Butterell's list in the Naturalist for December. Ancylus 

 JluviatiUs occurs in the Hotham Beck, and in streamlets about Brough 

 and Welton. Vertigo edentula was found near Brough at the meeting of 

 the Yorkshire Naturalists' Union there. Helix rufescens can scarcely fail 

 •to occur. It is found at Goole, and our late recorder in conchology, the 

 Rev. R, D. Maxwell, took it at Bridlington. Conovulus myosotis should 

 be looked for in marshes by the Humber. Mr. Maxwell found an empty 

 shell among tidal debris on the banks of the Ouse at Goole, probably 

 washed up from below. The same gentleman also found two or three 

 small specimens of Tellina tenuis, dead, but containing the soft parts, so 

 that this species probably lives somewhere near the mouth of the Hum- 

 ber. If Mr. Butterell includes the Market Weighton canal in his area, 

 Unio pictorum and U. tumidus, which inhabit it, may be added to his 

 list, and it is very likely that Sphcp,rium rivicola and the Paludinm 

 would reward a search in the same locality. — H. F. Parsons, Goole. 



