ADMINISTRATIVE FUNCTION OF THE NUCLEUS 33 



las soon, however, as the chloroplast begins to divide, the nucleus 

 assumes its normal position in the immediate vicinity of the developing 

 chlorophyll apparatus. These facts seem to indicate that growth and 

 division of chloroplasts are, to some extent at any rate, controlled 

 by the nucleus. 



A still more convincing argument in favour of this view is 

 furnished by Gerassimoffs observations upon Spirogyra. Gerassimoff 

 has devised a method which will be described below for obtaining 

 cells of Spirogyra furnished, either with two nuclei, or else with a 

 single nucleus which is nearly twice as large as the nucleus of 

 a normal cell. In such cells the ribbon-shaped chloroplasts are 

 broader, more twisted and provided with more numerous marginal 

 lobes in the neighbourhood of the nuclei than towards the 

 ends of the cells. Moreover, these chloroplasts produce lateral out- 

 growths, which detach themselves from the parent organ and 

 develop into independent chloroplasts ; for this reason, cells with the 

 double allowance of nuclear substance usually contain from eleven to 

 fourteen chloroplasts in extreme cases as many as sixteen as com- 

 pared with the seven to nine which are present in normal cells. 

 Gerassimoff is undoubtedly justified in attributing the difference in 

 the development of the chlorophyll apparatus in the two cases to 

 nuclear influences. 



It is only reasonable to suppose, that the nucleus can exert such 

 localised influences as have been illustrated by the preceding examples 

 with the greatest certainty and efficiency, when it lies in close proximity 

 to the site of the process affected ; at the same time, there is no reason 

 why a similar controlling influence should not in other cases be trans- 

 mitted over considerable distances. The author has already pointed 

 this out in his treatise on " The Relation between the Position of the 

 Nucleus and its Functions," where he describes a number of cases, in 

 which protoplasmic strands, connecting the nucleus with the growing 

 region of the cell-wall, may serve to transmit stimuli from the con- 

 trolling organ to the site of growth. The cystolith cells of Ficus 

 elastica provide a case in point. Here the nucleus rests against the 

 inner wall of the young cell, exactly opposite the peg of cellulose which 

 forms the basis of the cystolith ; almost invariably, however, the 

 nucleus is connected with the peg by means of a special strand of pro- 

 toplasm. Another aspect of the same phenomenon has been described 

 by Miehe and Strasburger, among others ; these observers state that 

 the ectoplast is frequently connected to the nucleus by " kinoplasmic 

 filaments," particularly in the case of embryonic cells. The proto- 

 plasmic threads connecting nuclei with chromatophores (especially with 

 chloroplasts), which have been noted by Lidforss as occurring in a 



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