1891.] MICROSCOPICAL JOURNAL. 155 



numerous branching strands of protoplasm. In these strands the 

 granules can be seen circulating up antl down the strands and out upon 

 the lining. Here, then, we have the second power of protoplasm mo- 

 tion, but not a motion w^hich alters the shape of the cell. Upon the 

 surface of the leaf of Venus fly-trap, a plant which grows in the bogs of 

 North Carolina, there are sensitive hairs, the slightest touch upon which 

 is followed by the instant closure of the two halves of the leaf. Here 

 must be irritable cells. The cells of the potato tuber are very thin walled 

 and in the grown cells the protoplasm has disappeared, and the cells 

 were full of starch, a product of the anal)olic power of the protoplasm. 

 The cells of the bean seed-leaf are filled with albumen grains, another 

 substance produced by the anabolic power of cell protoplasm. Plant 

 cells in general are notable for the high degree to which they have spe- 

 cialized the anabolic function, and they can make multitudes of com- 

 pounds from the simple mineral ingredients of the air and soil. Ani- 

 mal cells on the contrary have in general specialized the motor and 

 irritable functions, though they have by no means discarded the meta- 

 bolic functions, but in animal the katabolic functions predominate and 

 elaborate compounds enter their body which were prepared bv plant 

 cells and comparatively simple compounds leave it. 



Resume. — We, then, are permitted to regard the cell as a being 

 endowed with the powers already consideredas belonging to this mys- 

 terious substance, protoplasm, and we find that bodily structure of 

 either plants or animal introduces us to these elements operating various 

 of these powers. We shall next consider some of the conditions of cell 

 life and the results of combined effort and division of labor among cells, 

 or, in other words, tissues. 



[7o be continued.^ 



Examiiiatiou of Insect Powder.* 



By N. J. NITZSCHMANN, Ph. G. 



Persian or Caucasian insect powder consists of the flowers of Py- 

 rethrum carneum and P. rose?itn growing upon the Caucasian Moun- 

 tains, at an elevation of about a mile. Dalmatian insect powder is the 

 product oi P. cincrariiV folium, and it is more powerful than the Cau- 

 casian powder. Insect powder does not appear to be poisonous to man, 

 though it is said to cause some confusion of the head in those who sleep 

 in close apartments where much of it has been used. 



It has been held until very recently that insect powder owed its in- 

 secticide properties to the minute subdivision in which the particles 

 existed, and that they acted mechanically by clogging and filling the 

 air-passages. Late investigations, however, have settled the fact that 

 though the powder does act in this manner to a certain extent, its great- 

 est insecticidal properties are due to a true poisonous principle whose 

 nature has not been positively determined. Some claim that it is an 

 alkaloid, while others say that it is a soft resin. The powder exhausted 

 by means of alcohol is harmless to insects, while the fumes of the burn- 

 ing powder is very destructive to them. 



Insect powder has been used as a dressing for ulcers and wounds to 

 prevent the formation of maggots. It also answers to preserve dried 



•Read before the St. Louis Club of Microscopists. 



