150 Descendenz und Hybriden. 



une longue serie de generations cellulaires successives jus- 

 qu'aux cellules germinales. 



Coutagne appelle mnemons de ai et de a2 les 

 facteurs elementaires de l'heredite de ai et de a2. 

 Ces facteurs sont supposes posseder une certaine autono- 

 mie tout au moins temporaire compatible meme avec 

 le theorie biochimique; toute hypothese complementaire sur le 

 nombre, la nature et le mode d'action des mnemones est 

 ecartee de la definition. 



L'idee de mnemons distincts cohabitant dans l'oeuf 

 feconde et dans les blastomeres qui en derivent est donnee par 

 l'heredite des caracteres polytaxiques. Coutagne appelle 

 polytaxique tout caractere variant d'une facon discontinue, 

 c'est ä dire presentant plusieurs modalites nettement 

 disjointes, plusieurs taxies. Chaque taxie differente semble 

 determinee par un sorte de mnemon. Mais il n'en est peut- 

 etre pas de meme pour les differentes modalites dont sont 

 susceptibles les caracteres non polytaxiques. Toutefois il est 

 presumable que ces modalites sont determinees par un 

 mecanisme ayant tout au moins quelque analogie avec celui de 

 la determination des taxies. A. Giard. 



Eaton, A. A., New Varieties of Isoetes. (Rhodora. Vol. V. 

 November 1903. p. 277-280.) 



Recent collections have not only extended the known geographical 

 ranges of certain species of Isoeies but have shown also that there have 

 been developed in proximate drainage areas sorts which, though pre- 

 senting constant or slightly varying differences, are apparently from a 

 common stock and are not of specific rank. These may be considered 

 as incipient endemic species, the development of which has been con- 

 trolled in some measure at least by topographic conditions. The follo- 

 wing (the type specimens all from Massachusetts) are described as 

 new: /. saccharata Amesii, I. Canadensis Robinsii, I. foveolata pleno- 

 spora. Maxon. 



PEARSON, K., Cooperative Investigations on Plant s. 

 I. On Inheritance in the Shirley Poppy [drafted 

 by K. Pearson]. (Biometrika. Vol. II. p. 56—101. 1903.) 



This paper gives the results of experiments on the Shirley 

 poppy. Crops were grown on the Chilterns in 1899 and at 

 Chelsea in 1900. The plants of each crop shewed great incli- 

 viduality and there was considerable difference between the crops. 



Crops were in 1900 grown in eight different districts from 

 the seeds of the original Chilterns crop, the seeds were collec- 

 ted in three ways (I) all the seed from every capsule of 24 in- 

 dividuals out of 176 plants, this is known as Individual Plant 

 Seed; (II) the seed from the capsules of a great variety of 

 poppies sorted into groups of capsules having 8 to 18 bands, 

 known as Individual Band seed; (III) seed from all capsules and 

 plants without discrimination or the general seed; later another 

 type (IV): Individual capsule seed, was used. 



