556 L. R. CRAWSHAY. 



Copepoda alive in the Laboratory met with Kttle success. Mention may 

 here be made of one important result obtained by Dr. Allen himself, 

 in the course of his Diatom experiments. In a flask of 1000 c.c. in capacity 

 he kept, between August and September, 1905, some specimens of 

 Calanus f^mnarchicus alive on a mixed Diatom culture for a period of 

 about seven weeks, and obtained from them many nauplii, two of which 

 developed into young Calanus, of which the exact life period was not 

 recorded.* It was uncertain how far the exact conditions under which 

 this experiment was carried out had been essential to its success, and 

 with a view to locating harmful influences and removing them as they 

 became apparent, the experiments came to be conducted under many 

 different conditions in regard to position in the Laboratory, the kind 

 of vessel employed and its capacity, the water used, the intensity of the 

 light, the food culture, and the presence or absence of an air supply. 

 Attention was also given to the question of the influence of some of the 

 Bacteria and their destruction. Only after a large number of experi- 

 ments had been made was it ascertained that due consideration had 

 not been given to a factor, the importance of which cannot be over- 

 estimated, namely, temperature, and that to irregularities of temperature 

 the repeated failure of the earlier experiments was without doubt to be 

 attributed in a very large degree. The work which has since been re- 

 sumed still needs careful attention to details of method before satis- 

 factory results can be obtained, and in the meantime a short account 

 •of the experiments is given as a preliminary contribution to the subject. 

 The experiments will be considered, as far as may be, in the order 

 in which they were carried out, while grouping them together according 

 to different conditions, some reference to which is first necessary. 



Position. 



(A) In this room, where most of the earlier experiments were 

 made, the aspect is north and the light moderate. The window was 

 at all times kept partly open, and no artificial heating was used ; conse- 

 quently the experiments w^ere very susceptible to outside changes of 

 temperature that occurred from one day to another. Records of the 

 temperature of the water of the experiments were not made till the 

 latter part of November, but twenty-five observations made between 

 November 26th and January 13th showed a varying range of 6° or more,f 

 a maximum daily variation of 3-8°, and a maximum change over two 



* Journ. Mar. Biol. Assoc, N.S., Vol. VIII., p. 470. 

 t All temperatures are recorded in degrees Centigrade. 



