556 



SCIENCE 



[N. S. Vol. LI. No. 1327 



approximate equality of births and deaths — 

 nevertheless the biological changes induced by 

 the war, as expressed in this ratio, were the 

 same for the one as for the others. We are 

 evidently dealing here with deep-seated and 

 fundamental phenomena of racial biology. 

 The biological reactions of French and Ger- 

 mans in respect of a most fundamental phe- 

 nomenon, the death-birth ratio, were essen- 

 tially the same, though they started from such 

 different pre-war bases. 



The case of England is obviously entirely 

 different. Starting from about the same base 

 as the German states England's biological re- 

 action to war was much less pronoimced. 

 There are many explanations, such as better 

 food conditions, different race psychology from 

 any of the other belligerents, etc., which 

 might be brought forward. There appears at 

 the moment no way of accurately evaluating 

 any of these possible explanations. We must 

 perforce rest with the setting forth of the 

 facts. It is worth noting, however, that 

 though England's vital index changed less in 

 degree than that of the other countries, its 

 movement was the same in kind. 



There are two other points which one would 

 like to have information upon. The first is: 

 What will be the course of these death-birth 

 ratio curves in the years following 1918? 

 Will they come back to the pre-war level, and 

 if so, how soon? For England and Wales 

 alone is it now possible to get an indication 

 on this point. For the year 1919 the relation 



— =r; — ; had thc value 73 per cent. This 



Births 

 represents a marked drop, though it does not 

 bring the curve back to the pre-war level. 

 The appearance of official statistics which will 

 make possible the fiirther plotting of the 

 curves of Fig. 1 wiU be awaited with great 

 interest. In the second place, one would like 

 to know what the appearance of the curve for 

 the United States would be. Unfortunately, 

 we have for the Registration Area of births 

 data only for the years 1915, 1916, and 1917 

 now available. So few years appear inade- 

 quate to set against the longer series for the 

 other countries. Eaymoni) Pearl 



The Johns Hopkins Univeksitt 



COLORED PHOTOGRAPHS OF PLANT 

 DISEASE SPECIMENS 



In the preparation of a handbook of the 

 diseases of vegetables by the U. S. Bureau of 

 Plant Industry for the Food Products In- 

 spection Service of the U. S. Bureau of 

 Markets, it has been found practicable to 

 make colored illustrations by the aid of a 

 firm of commercial photographers.^ 



The specimens of diseased vegetables were 

 collected by the writers to a large extent in 

 the Chicago markets and freight yards. In 

 addition numerous field excursions were made 

 into the region surrounding Chicago for the 

 purpose of securing specimens. To date, over 

 two himdred illustrations have been com- 

 pleted, a number of which were exhibited at 

 the Baltimore and St. Louis meetings and 

 aroused a very general and real interest on 

 the part of the botanists. So many questions 

 were asked concerning the process by which 

 the illustrations were prepared that the writers 

 are using this means of making the answers 

 as generally known as possible. 



A vertical camera was used and the speci- 

 mens were arranged on a ground-glass back- 

 ground which eliminates shadows. Occasion- 

 ally a black velvet background was used, and 

 leaves usually were laid on wet blotting paper 

 to prevent curling. In making the exposures, 

 artificial light was seldom used. Most of the 

 subjects have been reproduced in natural size 

 on 8 by 10 inch negatives. The camera was 

 equipped with Cooke Process Lenses, Series 5, 

 of 16 or 18 inches focal length, or with a Goerz 

 Dogmar lens of 12 inches focal length. Color 

 filters, usually the Iv2 yellow or the green, and 

 occasionally the red, were used in about 75 

 per cent, of the exposures. About two-thirds 

 of the exposures were made on Seed's Pan- 

 chromatic plates and the remainder on Poly- 

 chrome or Standard Orthonon plates. The 

 legends are etched in the gelatin of the nega- 

 tive. The majority of the subjects have been 

 photographed in duplicate to insure against 

 loss of the record by breakage. 



Prints are made either on Defender or 

 Kresko printing-out paper or on Defender or 



1 Webster Bros., Chicago, Illinois. 



