WERNER MARCHAND 121 



Half pint jelly glasses were found by Hine to be well suited for the 

 purpose and easily obtainable. Covers proved to be desirable in 

 order to prevent too rapid evaporation of moisture, but a small per- 

 foration or two in them was necessary to furnish ventilation. As the 

 muck which was tested as soil for the Jars grew much mold, clean lake 

 sand was chosen as decidedly preferable for the purpose. The cov- 

 ering of plant material mentioned furnished a resting place for the 

 small crustaceans offered for food, and the larvte themselves seemed to 

 choose to remain in it in preference to burrowing into the sand, al- 

 though they were apt to be found in any part of the jar. Algae made 

 good material for covering, but only a small amount could be used, 

 and too much water was detrimental as either in excess tended to 

 cause decay, and consequently a bad odor, which was observed to be 

 unfavorable to the insects. The principal point in favor of the algae 

 was that they contained no hollow stems or large pieces into which 

 the larvae could crawl, but still, being composed of small soft par- 

 ticles, furnished a mat in which they could hide. When it was de- 

 sired to locate these larvae it was easily done by picking the mass to 

 pieces. As odors, which are often fatal to the larvae, were likely to 

 develop from the material put in for food and also from other sources, 

 it was found necessary to watch the jars continually, giving them a 

 thorough cleansing once in a while, and perhaps putting in fresh sand 

 and plant material occasionally. 



Larvae when first hatched were about 2 mm. in length; they grew 

 rather slowly, but in fifteen days after hatching had doubled their 

 length. They fed readily on the small crustaceans which were given 

 them. It was impossible to give these small crustaceans their proper 

 surroundings, so many of them died, and it was observed that the 

 young larvae fed on these as well as on the specimens v/hich they 

 killed themselves. The larvae could be seen crawling about in the 

 jars; they appeared to remain very near the upper surface of the 

 sand most of the time, and when food was scarce did much crawling, 

 but when food was plentiful satisfied their appetites and hid among 

 the plant material where they remained quiet. 



A difference in size in the various larvae soon became apparent, and 

 the older they became the greater was this difference. On July 23, 

 twenty-five days after hatching, some specimens measured as much 



