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SCIENCE 



[N. S. Vol. XXV. No. 634 



(1) Agouti, GG, BlBl, RE, producing gametes G Bl E 



(2) Black, AA, BlBl, RE, " " A Bl E 



(3) Bed, AA, BB, RR, " " ABE 



(4) Eed, GG, BB, RR, " " GBR 



The cross between (2) and (3) gives AA, 

 BIB, EE, which is black. The gametes pro- 

 duced by this hybrid are ABIE and ABE. 

 The fortuitous union of these gives, in genera- 

 tion F,: 



1 AA, BlBI, EE; 2 AA, BIB, EE; 1 AABBEE, 



or 3 black and 1 red. 



The cross between (2) and (4) gives AG, 

 BIB, EE (agouti), producing gametes ABIE, 

 ABE, GBIE, GEE. The fortuitous union of 

 these gives: 



a) 1 AA, BlBl, EE ; (d) 2 AG, B1B1,',RE; {g) 1 GG, BlBl, RE ;; 

 (6) 2 AA, BIB, EE ; (e) 4 AG, BIB, EE ; (A) 2 GG, BIB, EE; 

 (c) 1 AA, BB, EE ; (/)2 AG, BB, EE ; (i) 1 GG, BB, EE 



This gives 9 agouti, 4 red, and 3 black. 

 If the cross (2) X (4) (= AG, BIB, EE), is 

 crossed with (3) (AA, BB, EE) we get: 



Gametes of (2) x (4) 

 ABIE X 



ABE I 



GBIR X 



GBR X 



Gametes of (3) 

 ABE = AA, BIB, RR (black) 

 ABE = A A, BB, EE (red) 

 ABE = GA, BIB, EE (agouti) 

 ABE = GA, BB, RR (red), 



or 2 reds, 1 black, and 1 agouti. Professor 

 Castle states that 4 types of reversionary 

 agoutis probably occur in the cross (2) X (4); 

 3 of which have been obtained in his experi- 

 ments. Table I. above, giving generation F^ 

 of this cross, shows that the type (e) (AG, 

 BIB, EE) occurs in four sixteenths of this gen- 

 eration, type (h) (GG, BIB, EE) in two six- 

 teenths, and type (d) (AG, BlBl, EE) in 

 two sixteenths. These are the three types he 

 found in his experiments. The fourth type, 

 (g) (GG, BlBl, EE) occurs in only one six- 

 teenth of this generation. The small number 

 of individuals in which this type occurs 

 doubtless accounts for the fact that it has 

 not yet been found in the experiments. 



From the formulae of these four types we 

 readily see why they behave as stated by Pro- 

 fessor Castle. Type (e) is the same as the 

 cross (2) X (4); and therefore gives, in gen- 

 eration Fj, 9 agoutis, 4 reds, and 3 blacks; 

 (h) produces gametes GBIB and GBE. 

 These uniting with ABE (red) give half AG, 



BIB, EE (agouti) and half AG, BB, EE 

 (red) ; (d) produces gametes ABIE and GBIE. 

 These uniting with ABE (red) give half AA, 

 BIB, EE (black) and half AG, BIB, EE 

 (agouti). The remaining tjrpe (g) is pure 

 agouti, and breeds true. 



The above formulae may seem complex at 

 first, but they are really quite simple, and 

 render the process of determining the char- 

 acter content of any cross and its progeny 

 exceedingly easy. 



One of the above crosses shows how two 

 characters that are not allelomorphic to each 

 other may still give the numerical relations 

 in generation F„ of a pair of allelomorphs. 

 An individual having the color black may 

 have the formula BlBl, EE, the red not being 

 noticeable because indiscriminately mixed 

 with, and concealed by, the black pigment. A 

 red individual may have the formula AA, EE, 

 in which A represents the absence of Bl. The 

 respective gametes are BIE and AE; the hy- 

 brid being ABl, EE, which is black. The 

 gametes produced by this hybrid are AE and 

 BIE. Fortuitous union of these gives : 



AE I AR = AA, EE (red) 



AE X B1E= ABl, EE1 ,i, , ,, u j x 

 BIE xAR =ABi; ERJCblMk-hybrids) 



BIE X BIE = BlBl, EE (black-pure) 



This is clearly the same result, as far as 

 color of progeny is concerned, as if Bl and E 

 were a pair of allelomorphs. "We know they 

 are not, since in the pure agouti type both 

 colors are present in such form as to be trans- 

 mitted to all the progeny. 



W. J. Spillman 



U. S. Department of Agricdltuee 



NOTES ON ORGANIC CHEMISTRY 

 diazoaminomethane (dimethyltriazine) 



Many members of the important class of 

 compounds known as the diazoamino deriva- 

 tives are known, but these, hitherto, have all 

 belonged to the aromatic series. Otto Dim- 

 roth' has, however, recently succeeded in iso- 

 lating the first and lowest representative of 

 the aliphatic division — diazoaminomethane or 

 dimethyltriazine, as it may also be called, 

 CHjN :]Sr]SrHCH3. The compound is interest- 

 ing not only for the reasons given, but also on 



'Be?-, d. Chem. Ges., 39, 3905 (1906). 



