116 CARNEGIE INSTITUTION OF WASHINGTON. 



collaboration with the Eugenics Record Office and Hon, James J. Davis, 

 Secretary of Labor, at the expense of the Department of Labor. These 

 studies were based upon the records which we have accumulated, and were 

 on the subject of the several aspects of selective immigration. 



THE PHYSIOLOGY OF REPRODUCTION AND DEVELOPMENT. 

 Modification of Length of (Estrus Cycle by Means of Alcohol. 

 As described in the Year Book for 1921, Dr. E. C. MacDowell found that 

 when both parent rats were given alcohol before and during mating they 

 produced nearly 11 per cent fewer progeny in a litter than their full brother 

 and sister controls. Moreover, in an equal period of time the alcoholized 

 parents produced 0.72 litter per pair, while the unalcoholized mice produced 

 2.07 litters per pair. Thus the alcoholized parents had about one-third as 

 many litters and seven-eighths as many young to the litter as the unal- 

 coholized. Consequently, in a struggle between the two kinds of parents, the 

 former would tend to succumb through insufficient numbers. An approach 

 to the problem of the influence of alcohol upon the prolongation of the inter- 

 val between litters, hence probably of the oestrus cycle, was provided by the 

 notable work of Long and Evans on the oestrus cycle of the rat and of Edgar 

 Allen on that of the mouse. These workers show that the method of vaginal 

 smears is adequate in measuring the oestrous cycle. Dr. MacDowell is con- 

 tinuing work on the causes of reduced fecundity of the alcoholic mice. He 

 reports as follows: 



"Mice have been used in the present study on account of the larger number 

 that can be raised in the same space and on the same food as rats. Daily 

 vaginal smears are taken by means of a very small swab and examined micro- 

 scopically after staining in hemotoxylin and eosin. The alcohol has been 

 given by the inhalation method as before, but instead of tanks holding 

 numerous animals, a pint milk-bottle has been used for each mouse; a meas- 

 ured amount of alcohol is poured over a standard-sized piece of paper toweling 

 which is then slipped into the bottle after the mouse, and a regular milk- 

 bottle stopper is inserted and the bottle inverted. The controls, which 

 live in the same boxes with the corresponding treated mice, are handled in 

 the same way, with the omission of the alcohol. Three series of experiments 

 have been in progress: (1) Starting when the mice are a month old, they 

 have been placed in bottles with 3 c.c. alcohol on the paper every day for 

 45 minutes, called the light dose; (2) month-old mice have been given the 

 3 c.c. dose every day until they were motionless and did not move when the 

 bottle was rotated, called the heavy dose; (3) starting after a series of normal 

 cycles had been obtained from the mice as adults, the dose of 3 c.c. for 45 

 minutes was given, and later in some cases the heavy dose was given. 



" So far the following numbers of mice in the respective series have been 

 studied: 50, 13, and 11. The average number of observed cycles per mouse 

 is 5. When the treatment is started early and given for 45 minutes per day, 

 the summaries of the results obtained show no general modification of the 

 length of the oestrous cycle in the treated mice compared with their untreated 

 sisters. The time of the original opening of the vagina and the time before 

 the first observed oestrous seem to be equally unmodified by the Hght treat- 

 ment. The number of cycles so far obtained from the young ones given the 

 heavy dose is too small to venture a preliminary conclusion. Although there 

 may be no general effect shown by the alcohol treatment, there are marked 

 individual cases that appear to indicate marked effects; giving records of 



