136 Number of Chromosomes in Lathyrus 



and independently living individual, as for instance in the liverworts. 

 This I have already pointed out in a previous work : '* The Chromosomes. 

 Their numbers and general importance" (Comptes rendus des travaux 

 du Lahoratoire de CoHsberg, Vol. xiii, Copenhagen, 1917). A species 

 such as Marchantia polymorpha, with eight chromosomes, would thus 

 only form, at the outside, 256 types on crossing between two individuals; 

 and by taking an individual of a monoecious species, self-fertilised, 

 then eo ipso we should obtain but one type — a pure line — if we may use 

 this term also for cultures of haplobionts. 



Lathyrus odoratus is one of the plants with which we may hope 

 sooner or later to elucidate the important question as to agreement of 

 reduction division with Mendelian segregation, as students of genetics 

 have for a long time back been occupied with the genotypic features of 

 this species. 



Acting upon a suggestion from Prof R. C. Punnett, of Cambridge, 

 concerning the number of chromosomes in Lathyrus odoratus, I proceeded, 

 in the summer of 1918, to fix and examine material of the species in 

 question. In a written communication to me, Prof Punnett stated that 

 Mr R. P. Gregory had informed him that there were doubtless seven or 

 eight chromosomes in the haplophase. Otherwise, as far as I am aware, 

 nothing is stated in extant literature as to this ; no mention is made as 

 to any species of Lathyrus either by Tischler in his excellent " Chromo- 

 somenzahl, -Form und -Individualitat im Pflanzenreiche " {Progr. Rei 

 Bot., Vol. V, 1915, p. 164) or by Ishikawa in his likewise very compre- 

 hensive work, "A list of the number of chromosomes" (The Bot. Magazine, 

 Tokyo, Vol. XXX, 1916, p. 404). 



On two occasions, in the early spring and early summer of 1918, 

 Prof Punnett sent me, from his cultures at Cambridge, freshly fixed 

 material of young flowers of L. odoratus. On investigation, however, 

 the former consignment was found to be at a too advanced stage, as the 

 tetrad division had throughout been completed. The second batch of 

 material, again, was too young, no stage beyond synapsis being discernible. 

 In order not to delay the investigation further by correspondence under 

 the present abnormal conditions prevailing in the postal service, I 

 therefore fixed material myself, obtaining it from a garden at Marselis- 

 borg, near Aarhuus (Jutland) in the month of July. The material was 

 fixed in Carney's liquid, and stained with Delafield's haematoxylin. 

 Besides the above mentioned species, I also fixed, in September, by the 

 same means, some young flowers of Lathyrus latifolius, cultivated in the 

 experimental nursery of the Carlsberg Laboratory, Copenhagen* 



