﻿3 1 2 BOTANICAL GAZE TTE [may 



lymph. These lacunae nicrease in size, flow together, and 

 appear to force the surrounding chromatin outward. This 

 gradual increase in the amount of karyolymph is well shown in 

 figs. 4 and 5. Fig. 4. shows a large central cavity in the chro- 

 matin mass, and the whole takes on a ring-like appearance in 

 section. Fig. 5 show^s this still further developed, with two cavi- 

 ties filled with karyolvmph. The chromatin here is doubtless 

 preparing to take on the spirem condition of the ordinary rest- 

 ing nucleus. These stages [sec figs, j, 4, j, 6) clearly show that 

 this change in the shape of the chromatin is closely associated 

 with the accumulation of the karyolymph. Up to the stage 

 shown in fig, 5 no change whatever could be detected in the 

 cytoplasm that would indicate the formation of a membrane, 

 although up to this time the chromatin has been in close touch, 

 on all sides, with the cytoplasm. In fig. 6, however, is shown a 

 stage in which the karyolymph has increased to such an extent 

 and the chromatin has become so divided that the latter is no 

 longer immediately surrounded by cytoplasm. Here for the first 

 time the karyolymph comes in direct contact with the cyto- 

 plasm, and here also we have the first indication of a membrane. 

 As shown in fig, 6, the membrane does not completely surround 

 the chromatin, but is only observable at that region w^here the 

 cytoplasm is directly exposed to the karyolymph. By the s 

 greater increase in the amount of karyolymph which is accom- 

 panied by a still greater change in the shape of the chromatin 

 {fi£^s. 7, 8), this exposed region increases until the chromatin is 

 completely surrounded by the karyolymph [fig^ /), and the lat- 

 ter becomes exposed to the cytoplasm on all sides. A complete 

 series of stages was carefully examined^ and it was found with- 

 out exception that just as soon as a cytoplasm becomes exposed 

 to the karyolymph there a membrane is formed, and where this 

 exposed surface grows by the greater accumulation of the karyo- 



m 



lymph the membrane increases accordingly. The result of this 

 is a large central vacuolar structure [figs. 8, ij) containing chro- 

 matin in the spirem stage and commonly recognized as the rest- 

 ing condition of the mature nucleus. 



While the formation of the nuclear membrane was most 



till 



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