82 



MORPHOLOGY OP ANGIOSPERMS 



The Number of Chromosomes — Continued 



Plant. 



Orchis mascula 



Himantoglossum Mrcinum 

 Oymnadenia conopsea. 



Listera ovata 



Neottia nidus-avis 



Nymphaea alba 



CeratophylUim submersum 



Aconitum Napellus , 



Htlleborus foeiidus 



Paeonia spectabilis 



Podophyllum peltatum. . . 



Alchemilla alpina * , 



Asclepias Cormiti , 



tuberosa 



Asperula 



Crueianella 



Antennaria alpina* 



' ' dioica 



Siiphium integrifolium . . . 

 " laciniatum 



CHROMOSOME NUMBERS. 



Gameto- 

 phyte. 



16 

 16 



16 

 16 

 16 

 32 

 48 

 12 

 12 

 12 

 12 

 12 



8 

 32 

 10 

 10 

 12 

 10 

 40-50 

 12-14 



8 



8 



Sporophyte. 



(32) 

 (32) 

 (32) 

 (32) 

 (32) 

 (64) 

 (96) 



24 

 (24) 



24 



mostly 16 



(24) 



16 



32 



20 



20 



24 



20 



40-50 



counted 20 



(16) 



16 f 



Observer. 



Strasburger 20 



Guignard 26 



Guignard 59 

 Strasburger 72 

 Strasburger 108 

 Overton 28 

 Strasburger 20 

 Strasburger 30 

 Overton 28 

 Mottier s * 

 Murbeck 94 

 Strasburger 96 

 Prye" 

 Lloyd 105 



Juel 88 



Merrell 77 

 Land 81 



Year. 



1888 

 1888 

 1888 

 1891 

 1891 

 1898 

 1900 

 1902 

 1893 

 1888 

 1894 

 1893 

 1895 

 1901 

 1901 

 1901 

 1902 

 1902 

 1900 

 1900 

 1900 

 1900 



It is evident from the table that Strasburger and Guignard 

 were pioneers in this work and that they still remain the most 

 active contributors. It is of interest to note that when atten- 

 tion was first directed to this subject, the number of chromo- 

 somes reported for the sporophyte, while exceeding that of the 

 gametophyte, was not precisely twice that number. The sub- 

 ject is one of great difficulty, and doubtless the countings of 

 competent investigators have often been influenced by their 

 theories, while their followers have been content too often with 

 confirming a reported number. Variations from the character- 

 istic number are numerous. In the gametophyte the number 

 of chromosomes in the antipodals is frequently irregular, with 

 a tendency to higher numbers ; but an explanation may be found 

 in the irregular nuclear divisions which present some of the 

 characters of amitosis (Miss Sargant 41 ). Variations are even 

 more frequent in the sporophyte, but it is well known that 

 mitoses are frequently irregular, and it is easy to imagine that 

 a chromosome may fail to split or that an unequal distribu- 



* Parthenogenetic. 



f More than 16, probably 24, in endosperm. 



