ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 733 



Supposed new species of Cristatella.* — E. Potts describes the 

 discovery of aggregations of colonies of a species of Cristatella (C. 

 lacustris) appareutly differing from C mucedo of Europe and C. Idee 

 and C. ophidioidia of America. He considers it to be at least as 

 clearly ditfereutiated from any of the other species as they are from 

 each other, though probably, as the differences existing amongst them 

 are not considerable, all should be merged under C. mucedo. 



Arthropoda. 

 a. lusecta. 



New Type of Elastic Tissue, observed in the Larva of Eris- 

 talis.f — H. Viallanes has directed his attention to the curious 

 movements of the respiratory tube which is found at the end of the 

 body in the larvae of Eristalis. It is formed of a number of cylinders, 

 which can be shortened or elongated at the will of the animal : the 

 elongation is effected by the contractions of the body, by means of 

 which fluid is driven into it, and its shortening by special muscles 

 and internal elastic bands. Each of these elastic bands is formed by 

 a single cell, which is so constructed as to act as a piece of caout^ 

 chouc. The cell is fusiform in shape, and, while one of its extremities 

 is attached to the neighbouring integuments, the other is prolonged 

 into a process which is fixed to the inner face of the respiratory tube. 

 The cell and its prolongation are invested in a membrane, which is of 

 some thickness, but is very elastic. At the centre of the cell there is 

 a very large spherical nucleus, which is surrounded by a quantity of 

 protoplasm, which is also found in the prolongation. Within the cell 

 itself there is developed a long elastic fibre, similar in its physical 

 properties to those seen, for example, in the cervical ligament of a 

 mammal ; it is folded a large number of times around the nucleus, 

 and passes in a straight line through the prolongation of the cell, to 

 the extremity of which it is attached ; by the other it fuses with the 

 protoplasm of the cell. When the cell is drawn out the coiled 

 portion becomes unfolded. 



The facts detailed are of interest, as proving the high degree of 

 complexity that may be attained within the limits of a single cell, 

 and as throwing a new light on the morphology of elastic tissue, 

 since they show that this may be, as in vertebrates, developed in the 

 intercellular substance, or, as in Eristalis, in the protoplasm itself. 

 It may be noted that striated muscular tissue presents analogous 

 variations. 



It would seem, then, that the same tendency obtains in elastic as 

 in muscular tissue ; in both cases, perfection is attained by parts 

 leaving the protoplasm of the cells to which they primitively be- 

 longed, and, by becoming intercellular, being converted into the 

 undivided property of neighbouring cells. 



Submaxillary of the Jaw of Mandibulate Insects.^ — J. Chatin 

 retains the name of submaxillary for the part of the buccal apparatus 



• Proc. Acad. Nut. Sci. Philad, 1884, pp. 193-9 (1 p].). 

 t Comptes Rcndua, xcviii. (1884) pp. 1552-3. 

 X Ibid., xtix. (1884) pp. 51-3. 



