ZOOI.OGY — castIvE; and mark. 243 



fellow in biology in Harvard University, who has both provided means for 

 greatly increasing the number of animals under observation and has kept the 

 records of the experiments with great care. 



The valuable material and surgical assistance of Dr. Phillips has also made 

 possible a new line of experiments of much theoretical interest, in the trans- 

 plantation of germ-cells from one mammal to another. Contrary to some 

 earlier but in our view uncritical experiments with birds and mammals, we 

 have been able to show that the ovary transplanted from one animal to 

 another probably retains its original character without modification by the 

 changed environment of the body into which it was introduced. Out of many 

 experiments we have as yet obtained one positive result. An albino female 

 guinea-pig into which were transplanted the ovaries of a black guinea-pig 

 bore a litter of two black-pigmented young sired by an albino male guinea- 

 pig. Since normal albinos produce only albino young, it is evident that these 

 young developed from ova liberated by the introduced ovaries. Further, 

 their character was such as might have been that of young borne by the black 

 guinea-pig herself had she been mated with the albino male in question, in- 

 stead of merely furnishing ovarian tissue to the albino female. Sweeping 

 generalizations must, of course, not be drawn from this single case, but it 

 certainly does not favor the view that environmental influences can directly 

 induce germinal ones. 



The experiments with mice, in charge of Mr. C. C. Little, have shown the 

 existence of two different modifications or "dilutions" of the pigmentation, 

 which behave as independent Mendelian characters in heredity. In one the 

 coat is pale, but the eye pigmented; in the other the pigmentation of both 

 coat and eye is affected. The case, however, can not be explained by the 

 assumption of an independent factor for eye-pigmentation different from that 

 of the coat, as Cuenot has suggested, for each modification actually affects 

 the coat pigmentation, but in a different way. Three papers have been pub- 

 lished this year (see Bibliography, page 49) and two are now in press. 



Castle, W. E., and Mark, E. L., Harvard University, Cambridge, Mass. 

 Grant No. 492. Continuation of experimental studies in heredity. (For 

 previous reports see Year Books Nos. 3, 4, 5, 6, and 7.) $Soo. 



A separate grant has been made to Dr. Castle for the continuation of his 

 work in this field. 



Dr. Mark reports that, owing to the heavy duties of instruction assumed 

 by Dr. Copeland at the beginning of last year, it was impossible for him to 

 revise for publication the paper on the "Spermatogenesis of the Honey Bee 

 and the Wasp," which was nearly ready for the printer a year ago. In its 

 revised form this paper will, however, be soon submitted for publication. 



In accordance with the plans stated in his report for 1907-08, Dr. Mark 

 has given time chiefly to the study of the hymenopterous parasites of the 



