

Neuromot or Apparatus in 



42] 



MACRONUCIJ 



The outline anil structure tit' tin- large ('-shaped macroiiucleus 

 appears in the living, unstained organism very much as in the lixed 

 material figured and deserihed liy Yocom ( HUSK The "contraction 

 phase" cil' this organ with its reconstruction bands may be clearly 

 observed in animals free from too many food vacuoles. Hut these 

 features and partimlarly the granular, mesh-work consistency of the 

 inaeronni-leus can be much more satisfactorily studied after the latter 

 has been dissected out with the needle. It is then found to be a highly 



r rt.p. 



mac. 



Fi'j. H. Tlio nuclei of E>i/ilnlix. ,-.< .. cut end: <;/ crtoplasmic granules; mac., 

 niiicronurleus; HH'C.. micronucleus; n.p., nci'illc point. 



irelatinoiis. rather rigid struoture composed of small granules imbedded 

 in a viscous, hyaline matrix (text fig. B). The organ is enveloped by 

 a very thin, structureless membrane. 1'pon exposure to the water, the 

 macronudeus increases slowly in size; within hall' an hour or so small 

 blisters of the membrane slowly appear over the surface; the rate and 

 extent of swelling increases and. upon rupture of the membrane in one 

 or several places, there follows a rapid dissolution of all except the 

 small granules, which for several hours exhibit a dancing Hrownian 

 movement. These granules vary somewhat in size, with an average 

 diameter about one fourth that of the microsomes found in the 

 endoplasm. 



