June 25, 1897.] 



SCIENCE. 



985 



due more to the method of application than 

 to defects of the principles involved ; for, 

 as stated, by the use of dried blood, as in 

 our experiments, it is not possible to make 

 the test with constant and accurate, or even 

 approximately accurate, dilutions of the 

 serum. Our irregularities may be in part 

 due to this defect. "We therefore lay less 

 stress upon this than upon the other fea- 

 tures of our work. 



Adelaide Ward Peckham, M.D. 

 Laboratoey of Hygiene, 

 XJniveesity of Pennsylvania. 



THE VIRGINIA COLONY OF HELIX NE- 

 3I0EALIS. 



The now well-known colony of the Euro- 

 pean Helix nemoralis at Lexington, Va., has 

 twice before been the subject of articles by 

 the present writer. {Nautilus, November, 

 1889, and December, 1894.) It was shown 

 in these articles that many new variations, 

 diflferent from those observed in Europe, had 

 occurred ; and the colony consequently be- 

 came of great interest to students of evolu- 

 tion. Unfortunately, Professor Morrison, 

 who was studying these snails, removed 

 from Lexington in 1890, and, having the 

 misfortune to lose his collection by fire, paid 

 no further attention to the matter. It is 

 only now that I am, through the kindness 

 of Mrs. John M. Brooke, of Lexington, in a 

 position to give some account of the colony 

 subsequent to the date mentioned. 



In order that everj"^ reader may under- 

 stand what follows, I will explain the sys- 

 tem of band-formulffi used for recording the 

 variations. The typical shell has five bands 

 and the formula is 12345. The absence of 

 a band is indicated by 0, thus 10345. Two 

 or more bands united are bracketed to- 

 gether as (12)345. A rudimentary band is 

 expressed by a small figure below the line, 

 as 1,345. A split band is expressed by 

 doubling the number, as 123345. An extra 



band, not assignable to any of the normal 

 five, is expressed by a x , as 123 x 45. 



Mrs. Brooke sends me a series of shells 

 gathered by herself at Lexington in 1896 

 and 1897. They are as follows : 



A. With a yellow ground-color == UhelluJa. 

 mellula 1234.'5 70. 



" 123(45) 21. 



" 10345 10. 



" 1,345 9. 



" 12045 G. 



" 00000 5 sent, but 



Mrs. Brooke says they are 

 plentiful. 



" 12345 4. 



" 1O345 3. 



*" 12,3(45) nov. formula.. 2, the form- 

 ula shows only near the 

 mouth of the shell. 



" 12345 2. 



" (123)(45) 2, juv. 



" (12)3(45) 2, oneisjuv. 



*libellula (12)233^45 nov. formula,.. 1, the formula 

 shows only near the mouth. 



" 1233(45) 1. 



" 00345 1. juv. 



" I2O45 1. 



" 02345 1. 



" 123kx(45) 1. 



" 00300 1. 



" i0300 1. 



" 123,: (45) 1, juv. 



*" i( 22)045 nov. formula..l. 



B. With fawn-colored ground = petiveria. 

 petiveria 12345 t. ^brissonia, Mo- 



quin-Tandon. 



" 123(45) 1. = (K-erii'ma Locard. 



" (12)3(45) 1. = brookea, n. n. 



C. With pink ground = nibella. 

 riibellaOOOOO 2. Quitepale. Mrs. 



Brooke says they are extremely scarce. 



The three forms above marked with an 

 asterisk are new to the Lexington list, and 

 are all new formulas of the split-band type, 

 like the previously found new variations in 

 the colony. All of the rest were formerly 

 obtained by Professor Morrison. 



The examination of the above list brings 

 out the apparent fact that the new split- 

 band variations are now comparatively rare 

 in the colony, though still much more fre- 



