SOME PLANKTON STUDIES IN THE GREAT LAKES. 



131 



The first six weeks were spent in qualitative work, that is in making a list of the 

 animals and plants of the lake, in noting the way in which they were associated, their 

 habits, and in preserving - specimens, drawings, and records of observations. /Every 

 morning, and frequently again in the afternoon, a man was sent out into the bay, with 

 the different sorts of nets. With the tow nets were obtained the smaller animals and 

 plants floating in the water, at the surface, in mid- water and near the bottom. The 

 forms attached to the bottom or concealed among the water plants were collected by 

 means of the toothed dredge and by the Birge net. Collections were also made near 

 the shore with the same apparatus. All the materials were brought to the laboratory 

 and were- ready for examination upon the arrival of the laboratory force. Each 

 worker then sorted out from the collection the materials belonging to him. This 

 method of working was kept up until it was felt that all the inhabitants of the lake, 

 except possibly a few rare or occasional ones, had become familiar. The living speci- 

 mens were studied in all cases and material was preserved for future use. Final 

 identifications were attempted only in the cases where the original literature in the 

 laboratory was ample for the purpose. 



At the same time that collections were being made of the smaller inhabitants of 

 the lake, gill nets were set every day for the capture of fish, while other fish were 

 purchased from the fyke-net fishermen who landed their catch at the laboratory dock. 

 The stomachs of several hundred of these fish were examined and the contents pre- 

 served, with the purpose of determining the food habits of the fish. At the same time 

 the fish were systematically searched for parasites, and many important biological 

 data were collected concerning the parasites. A more detailed report on these para- 

 sites is in preparation by Dr. Ward. * 



In order to make a continuous and systematic record of the forms examined, use 

 was made of blanks in which each person entered the forms observed by him. The 

 blanks were of two kinds, one intended to give the important data concerning the 

 individual animals and plants and the other intended to show how these animals and 

 plants are associated under different conditions. The following is a sample of what 

 may be called the individual blank: 



-Specimen 



-Notes 117,124. 



-BOTTOM- 



-Vegetation 



NAME Sidat crystallina O. F.M. 



No. Drawing 



LOCALITY middle of Anchor Bay 

 HABITAT 



Pelagic Depth 



Littoral " 



Bottom x " 13 ft. " Clay " Characese. 



FOOD dinobryon ; diatoms; shells of both found in excreta. 

 ABUNDANCE moderate. 

 BREEDING $ ? $ with embryos & larvae in brood sac. 



HABITS ( dV not found. 

 REMARKS greenish transparent color is noteworthy. The grinding surfaces of mandibles 



suggest the crushing of diatoms. 

 DATE Aug 11, 1893 HOUR 7 a. m. SIGNT. J. E. Reighard. 



This blank gives the results of the observations of a single day on a single species 

 of Sida, the name of which appears at the top of the card. Whenever this species was 

 observed under different .circumstances a new card was made for it. By sorting all 

 the cards referring to a single species one has at hand in condensed form all the facts 

 recorded concerning it. 



* This report will appear as a bulletin of the Michigan Fish Commission. 

 t The words in this light-face type were added with the pen. 



