. Botanisk tidsskrift. Piante; piante -- la Danimarca. - 153 ward tipico synapsis stadio in cui la cromatina filettature sono spesso visto per essere disposti parallelamente gli uni agli altri e più tardi il fusibile e diventare uno o più fili di spessore. Il mandrino heterotypic figura in qualche modo devia dal suo corrispondente in H. padiglione auricolare. come i cromosomi sono significativamente ricca di numeri. Essi sono differenti per forma e disposizione, ma potrebbe in ogni caso essere classificata in bivalente e cromosomi monovalente, molto ricordando una di Drosera-hyhrid, precedentemente descritto da me (Rosenberg 22). Figg. 15 e IV A mostrerà più

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. Botanisk tidsskrift. Plants; Plants -- Denmark. — 153 ward typical synapsis stage in which the chromatin threads are often seen to be arranged parallel to each other and later fuse and become one or several thick threads. The heterotypic spindle figure deviates somewhat from its correspondent in H. auricula. as the chromosomes are significantly rich in numbers. They are different in shape and form, but could in any case be classified in bivalent and univalent chromosomes, very much reminding one of the Drosera-hyhrid, formerly described by me (Rosenberg 22). Figs. 15 and IV A will show more clearly the point in question. On account of the great number of chromosomes it is very difficult to determine their number with absolute accuracy. 1 have often found rather regularly 14 or 15 bivalent and 6 or 7 univalent chromosomes, whilst in other cases about 17 entirely bivalent chromosomes could be seen. I have long doubted as to how we can correctly value these very various spindle figures. In the beginning I found reasons which caused me to suppose that a hybrid from, two pa- rents with a different number of chromosomes, had to be reckoned with, but later I observed that my attention had to be given to a sort of division which could be regarded as an intermediate stage between reduction division and vegetative division. In the aforementioned Drosera-hyhrid always 20 bivalent and 10 univalent chromosomes could be recognized, whilst in this case a very great variation in the proportion of bivalent and univalent chromosomes could be found. It therefore seems to me very probable that in H. excelleus there is an incom- plete reduction process. I should like to express it in the following manner: the great number of chromosomes in each gonomer still keeps its ^affinity" and therefore can be united with its corre- spondent in the other, whilst a part, different in different nuclei, have lost that characteristic and were therefore univalent. It seems to me that already i

Parole chiave associate all'immagine

• bookcentury1800
• bookdecade1860
• bookpublisher
• booksubjectplants