850 



SCIENCE. 



[N. S. Vol. VIII. No. 20T, 



Office of Road Inquiry: Experiments in road en- 

 gineering. 



Office ^of Experiment Stations : Collection and 

 . dissemination of information regarding agricultural 

 education and research in the United States and other 

 countries. Supervision of cooperative investigations 

 on the food and nutrition of man and on irrigation. 

 Investigations on the agriculture of Alaska. 



The Library: Contains 63,144 volumes, largely on 

 agriculture and agricultural science. The library is 

 engaged in the preparation of bibliographies of sub- 

 jects in agriculture and agricultural science. 



Publications: During the year ended June 30, 

 1898, the Department issued 501 bulletins and re- 

 ports, the total number of copies being 6,280,365, ex- 

 clusive of the Yearbook, which has an edition of 500,- 

 000 copies, and also of the publications of the Weather 

 Bureau. 



A. C. True. 



THE BREEDING OF ANIMALS AT WOODS 



HOLD DURING THE MONTHS OF JUNE, 

 JULY AND AUGUST. 



During the month of June the tempera- 

 ture of the water continues the regular in- 

 crease which begins on the first of April, 

 and toward the end of the month reaches 

 the temperature of 65° F. During July of 

 the present year it fluctuated between 66° 

 F. and 71° F., and during August it fre- 

 quently registered 72° F. 



With the increased temperature of the 

 month of June there is a corresponding in- 

 crease in the number of breeding animals ; 

 indeed, this month indicates the culminating 

 point of reproductive activity of marine 

 organisms at Woods Holl. The months of 

 July and August are characterized by a 

 constantly decreasing number of breeding 

 animals, though the high temperature of 

 the water is conducive to the rapid growth 

 of innumerable larvaj. 



Verteh-ates. — Breeding lampreys have been 

 taken at East Taunton as late as June 17, 

 and the eggs hatch in from eleven to four- 

 teen days. The smooth dog-fish, Galeus 

 canis, frequently gives birth to ' pups ' while 

 confined in the ' fish cars ' during this 

 month. These young, beautifully marked 



swim about with their parents, and do nofe 

 seriously sufier from their restricted quar- 

 ters. The fishermen say that the ' smooth 

 dog ' has two broods, and the observations 

 made at the laboratories would indicate that 

 this view is correct. The first brood is 

 generally dropped during the early part of 

 June, though during the latter part of the 

 month a few females are often found with 

 fully developed young. It is probable that, 

 as soon as the young are born, mature eggs 

 leave the ovary and pass into the oviduct, 

 where they become fertilized. Professor 

 W. A. Locy has removed eggs from the ovi- 

 duct, which were in segmentation stages, 

 from as early as June 22 to as late as July 

 4. Through the early part of July the 

 embrj'os are small, but during August only 

 advanced stages are found. The second 

 brood may be dropped as early as August 

 10th. 



The belief that the females after giving^ 

 birth to their first brood immediately breed 

 again is supported by Dr. Ayers, who has 

 noted that there are congested placental 

 spots on the uterine walls of individuals, 

 the oviducts of which contain active sper- 

 matozoa, and Dr. Locy has noted that the 

 ovaries contain certain large ova during 

 June, whereas they contain only smaller 

 eggs after the early part of July. No 

 individual, however, is actually known to 

 have given birth to two broods in a single 

 summer. 



The sand shark, Carcharias liUoraUs, the 

 most common shark at Woods Holl during^ 

 the summer, so far as I know, has never 

 been taken during the breeding season, 

 all the individuals being apparently imma- 

 ture. The spiny dog-fish, Squalus acanthias, 

 though at times abundant during the early 

 spring, has not been taken in suflicienb 

 numbers during recent summers to be of 

 special value. Those desirous of collectings 

 embryological material of this species have 

 generally gone to North Truro, Province- 



