MICROSCOPY. 249 



Club, Professor E. P. Wright exhibited and described a sec- 

 ond species, marine, found growing and developing itself in 

 the mucilaginous tubes of a Schizonema. It is smaller in 

 size than (John's species, but with an emerald lustre scarcely 

 less than that of the fresh-water species. It seems to be 

 thus established that chlorophyi-bearing plants sometimes 

 need, and are capable of assimilating, already formed car- 

 bon compounds, hitherto supposed to be only a character- 

 istic of the fungi. 



In the Monthly Microscopical Journal for January, 1877, 

 Mr. Worthington G. Smith has an interesting paper called 

 " Notes on Pollen," and illustrated by four plates, which 

 show how extremely pollen grains differ in size, form, and 

 external marking;; oivin<r sometimes a valuable clue to a 

 plant's relationships, though sometimes pointing in various 

 contrary directions, since plants have not descended one 

 from another in a straight line, but possess complicated re- 

 lationships with plants belonging to several different natural 

 orders. 



In a paper read before the Royal Society and printed in 

 No. 179 of their Proceedings, Mr. F. Darwin, M.B., maintains 

 that the glandular hairs, or trichomes, found on both surfaces 

 of the leaf of the common teasel (Dipascus sylvestris) con- 

 tain true living protoplasm, inasmuch as they undergo vio- 

 lent contraction upon application of reagents of widely dif- 

 ferent natures, but not with osmic acid, which, it is well 

 known, is destructive of protoplasmic structures, and does 

 not cause them to contract. Under normal circumstances 

 the filaments appear animated by the perpetual tremble of 

 Brownian movement. The contraction commences by the 

 filament becoming shorter and thicker at a number of nearly 

 equidistant points, situated close together near the free end 

 of the filament. The beading spreads rapidly down the 

 filament, which ultimately runs violently together into a ball 

 seated on the top of the gland. Since the movements of the 

 filaments are not governed by forces residing within the 

 gland, but are composed of an essentially contracting sub- 

 stance protruded from the leaf-glands, the only theory which 

 seems capable of connecting the observed facts is that, while 

 the glands were originally only resin-secreting organs, the 

 protoplasm that originally came forth as a necessary coll- 

 ie 



