Kl NAR LÖNNBERG: Xc >TES ON SPIRULA RETICU1 VTA O 





sometimes to be found in one and the same cellule (Fig. i 4 a). It i that 



these arc products of an amitotic division, as 1 ha. | eus 



curved and contracted in the middle. A large transparent -ran,: l,t and 



stained, is very often, if not quite always, to be found lying, in n tl„ 



nucleus of the cellule (Fig. 14 a). We find also in these layei and 



finely branched system of capillary vessels with a thin homog< membrane and 



long nuclei in the same. These vessels are very soft and elastic, and dilations ol th< 

 walls arc frequent (Fig. 14). 



The longitudinal muscles have very long attenuated nuclei; these arc cylin- 

 drical or pointed at the tips. The original elements are divided in such a way that 

 quite a bunch of fibrils go to one nucleus. In the layer of these longitudinal mu 

 wc find some rather large cellules; they are myoblasts (Fig. 13). These cellules 

 give the origin to the muscular fibres, after which they are dum 

 that the last remains of them are the long and narrow nuclei in the muscular 1. 

 but all kinds of intermediate stages are seen (Fig. T3). 



The reticulated surface of the subcutaneous layers is very tough and d< 1 

 The reticulation itself is produced by masses of wavy fibres densely woven together 

 and running in various directions (Fig. 8) so as to form depressions or pits in the 

 interspaces. These depressions are not regular (Fig. 7) either in size or in shape. 

 The fibres are of connective tissue and we find nuclei scattered among them but n>> 

 cellules (Fig. 8). 



The circular muscles under this connective tissue arc composed of very strong 

 and thick threads each of them provided with an external sarcolemma containii 

 long nucleus imbedded in an interior bundle of fine longitudinal fibrils (I 

 When the thread is torn off, these fibrils can be seen isolated. The chromatoph 

 have the same structure as in other Cephalopods; a large nucleus is imbedded in 

 a dense mass of pigment granules. The chromatophores ai provided with ra- 



diating fibres which effect the dilation. At the point of insertion of these fibre- we 

 find one, or generally two, small nuclei corresponding to the "cellules basila 



Of GlROD. 



The fins arc small and rounded. They are inserted at th rior end ol 



the body. Their plane of attachment seems at first very strange for it is not hori- 

 zontal as in other Cephalopods, but nearly vertical 1 . This is however only a delu« 

 due to a ventral curvature of the posterior end of the body" in the sum direction 



1 The dorsal point of attachment is however a little more proximal than tl 



2 The tendency to such curvation of the soft parts arises of course at the same time 

 vation of the shell ! 



Festskrift fur l.illjeborg. 



