300 DISCOVERY REPORTS 



into a long pointed spur extending in the anterior direction of the host. In this respect the organ of 

 fixation of A. mnbeUatus corresponds exactly with that of A.fasciatus, in which Fage (1936) described 

 a similar excrescence. Moreover, \n A.fasciatus the organ of fixation has a number of shorter excrescences 

 of varying shape pointing in a lateral or posterior direction (Fage, 1936, fig. Wc). In all probability the 

 latter represent the proximal part of the root system, as they show a certain similarity to the corre- 

 sponding parts of A. umbellatus, where the large proximal roots are confined to the region of the 

 parasite turned towards the posterior part of the host. 



Fig. 10. Amallocystis umbi 



lomere, showing 



No Studies were made of cytological details of the parasite. A few remarks on the trophomeres 

 and the gonomeres may be given here. In the stained sections the trophomeres have a pink colour, the 

 younger gonomeres may have the same colour or may have become a slightly darker red. The older 

 gonomeres are stained much more deeply, and often show a dark blue colour. In the gonomeres 

 the nuclei appear to be more or less evenly distributed throughout the whole organ. In the tropho- 

 meres, however, there is a distinct difference between the proximal part and the distal region. In the 

 proximal part the nuclei are arranged in groups so as to form clusters that with their greater diameter 

 are more or less parallel to the longitudinal axis of the trophomere. This occurs in about the whole of 

 the proximal third part of the trophomere. In a more distal region the groups of nuclei become more 

 mdistinct, and finally the nuclei become more or less evenly distributed in the trophomere. The region 

 of transition of the groups of nuclei into a rather uniformly scattered mass of nuclei is shown for one 

 of the trophomeres in Fig. lo. It appears as if in the proximal region of the trophomeres the nuclei are 

 found on more or less parallel strands of tissue, whilst they do not occur in the intervening spaces. The 

 phenomenon referred to here is to be observed in all the trophomeres of the series of sections. 



