214 Cytology and Genetics of the Genus Fuchsia 



Some time ago I continued my studies of the cytological features 

 which are connected with the development of supernumerary pollen 

 grains in certain species and hybrids of Fuchsia and concurrently 

 I began a series of observations upon the genetics of the genus. 

 Circumstances have intervened and prevented the completion of the 

 work, but it was thought that it might be useful to future workers 

 if a brief statement were made of such results as were obtained, and of 

 the lines of work which appeared to promise interesting results. 



A. Cytology of Fuchsias. 



I will first describe the facts which are to be seen in a hybrid form 

 known as " Alice Hoffman." 



The early stages of the first meiotic division in the pollen sacs take 

 place in a normal manner as will be seen from PI. XXII, figs. 1 — 8. 

 The spindle which develops is apolar and the chromosomes become 

 arranged regularly at its equator at the conclusion of the prophase. 



During the anaphase, however, the chromosomes move very irre- 

 gularly towards the spindle poles and some, either singly or in groups, 

 lag behind the rest, and often become entirely cut off from the two main 

 chromosome groups. This irregular distribution of the chromosomes is 

 shown in figs. 9 and 10. At the conclusion of the division these 

 scattered and separated chromosomes behave variously. In the majority 

 of -cases distinct nuclei are developed in association with them. In some 

 instances only a single chromosome may become organised into a small 

 nucleus, but more commonly small groups of two or more chromosomes 

 are associated together in the development of a nucleus. The size of the 

 nucleus which is formed depends upon the number of chromosomes 

 which enter into it. Examples of such nuclei can be seen in figs. 11 

 and 12. In several cases the chromosomes were so scattered at the 

 beginning of the telophase that they did not lead to the formation of 

 a number of separate nuclei, but they all became included within a single, 

 large, irregular nucleus. In fig. 12 one small nucleus is seen to have 

 developed round a chromosome which had become widely separated 

 from its fellows, whilst all the remaining chromosomes were included in 

 the large irregular nuclear body which occupies the centre of the 

 mother-cell. Whilst it is more usual to find nuclei organised round the 

 scattered chromosomes there are other instances in which these bodies 

 degenerate without giving rise to a nucleus. In fig. 18 the chromosomes 

 excluded from the two principal groups are probably about to undergo 

 degeneration. All the nuclei, both small and large alike, enter upon the 



