Klc-.. 100 



Intestinal cell inclusions, A — Ifhiihditis slrnnffi/lititlfs (Living intestinal cell, surfaci 

 view : large radially striated rhabditin spliaerncrystals and small, snluble granules). B — Thfri/i 

 tuK «f/o.v?i* (Area of intestinal cell showing nucleus (not shaded], rhabditin sphaerocrystals 

 and olivaceous sphaeroids [small, sliaded|)_ C — Diti/leufhus dipffaci (Cell to left with foui 

 shaded nuclei, numerous colorless fat droplets and small black (actually purple] protein globule; 

 [stain, crystal violet]). D — Diploscupler cnrnnafn (fat globules black, olivaceous spliaeroid 

 shaded, nucleus colorless, crystals colorless. 



cuoles I osniic ] ) 



black, olivaceous spliac 

 Original. 



Rlitibditts monhystera. 

 1914, J. Parasit. v. 1(1). 



Flii. 101 

 Rhabditin sphaerocrystals 



seen in polarized light. .\fte 



erction; (2) it is itsi-lf a secretion iirodiu-t of jiroteetive na- 

 ture; (3) it is a layer of amalRaiiiat<'(l or degenerate cilia. 

 The second possibility seems least iirohable in the light of com- 

 parison by which one finds tlie layer very well developed in 

 forms ivhich hold to a liquid or semiliquiil diet (Ehahditis, 

 Trichiirif:) and is absent in some forms with a "solid" diet 

 (MelonchiiJdimiis). Quack (U>]:-li, following Biitseliii's alveo- 

 lar theory of protoplasm, held the bacilli of the bacillary and 

 suhtiacillary layers to be rows of vacuoles and not actual en- 

 tities, wliile Hetlierington (UtL>3) held the bacillary layer to 

 be cilia and the subbacillary la.^er basal granules. Upon the 

 basis of appearance and comparative morphology one must 

 conclude that Hetlierington 's view is the more probable. The 

 function is a problem for general zoology rather than nema- 

 tology. 



Prntoplasmic zones. — The presence of protoplasmic zones, 

 likewi.se, seems to be of no special significance in nematology 

 since differentiation into ectoplasm and eiidoplasin iL of wide- 

 spread occurrence in cells of living anim;ils. Certain authors, 

 such as K. (\ Schneider (1902), have seen fit to call the plasma 

 cap of Ascaris a "nutritorische zone." Quack has shown that 

 in Ascaris such material is not confined to the periphery but 

 extends into deeper parts of the cell as irregular masses 

 (plasma strands) in Ascaris and may l)e so distributed as to 

 form a mantel (Quack's fig. '21). fioldschmidt (1904) in- 

 terpreted the strands as a "Chromidiala|)parat " but Ilirschler 

 (1910), von Kemnitz (1912), and Quack (MILS) all have found 

 this to be an error. Quack found tliat starved specimens of 

 Ascaris showed no diminution in the plasma ca|) or plasma 

 strands and hence eliminated the iiossibility that the material 

 involved is absorbed albumen, concluding that it is differentiat- 

 ed functional cytoplasm (Compare Figs. 103.I-M). 



External coverings. — In large inyriocytons (see p. lO.'O nema- 

 todes one often finds a homogeneous, slightly basophilic layer 

 in immediate contact with the external cell surface, this layer 

 being termed the ha.ml lamella (Fig. 10.3.T7, ZC). Apparently 

 this layer is a differentiation acting as a suppcirting structure 

 or it is a secretion product of the intestinal epithelium. It is 

 not subdivided into areas corresponding to the cells and the 

 ectoplasm is attached to it rather than continuous witli it. 

 Fibrillar strands of the ectoplasm re.-ich its surface but do 

 not appear to enter into it as one might expect if it were 

 merely a differentiation of the outer cell surfaces. It acts 

 mure in the nature of a sheath and has affinity for collagen 



stains. At the present time there is no actual i)roof that the 

 basal lamella is formed by the intestine. Though such a layer 

 is plain in Ascaris, Pliji.ialiiplera, Tanqiia. Trichuris nntX Vioeto- 

 pln/ma, in other forms it is generally not visible. The extent 

 of its development is obviiuisly not correlated witli phylogenetic 

 relationships but rather with cell numbers for in all of the 

 above mentioned forms the intestine is myriocytous. 



In most free-living nematodes one can discern no distinct 

 mesenterial sheath over the intestine but in Dorylaimns as 

 well as in the ma.iority of parasitic nematodes an extremely 

 thin membrane isolates the intestine from the body cavity and 

 is termed the p.seudocoelomic membrane (see p. 4.t). Beneath 

 the membrane or mesentery, muscle filters may be present but 

 such fibers do not form a continuous layer and they are 

 usually confined to the posterior part of the intestine (]). 42). 

 However, in unusual instances they may form a c.iarse mesli 

 work (Fig. lO.SH) which in cross section gives the appear- 

 ance of a separate muscle layer. Such muscle fibers are classi- 

 fied as specialized somatic muscles rather than as a mK-iriilaris 

 niusra.^ae. 



B. MODIFICATIONS OF SUPERFICIAL 

 APPEARANCE; FORM OF LUMEN 



The superficial appearance of the intestine as observed in 

 toto depends upon the total number of cells, the character of 

 the cells and the character of cell inclusions. The shape of 

 the intestinal lumen is likewise dependent on the number of 

 cells, the form of the cells and whether or not they are equal 

 or unequal in height. 



Cki.i, Xumiikr. — Like the hypodermis and musculature, the 

 intestin<' of various nematodes presents a series of stages in 

 increaseil complexity: this series recapitul.-ites to a greater or 



101 



