by soldiers in Texas. The eg:g:s seen (Kofoid and White, 

 1919) were of the flattened type usually possessing large, 

 bluish-green globules at the end of the protoplasmic mass. 

 Sandground (1923) pointed out that these eggs belonged 

 to Hetcrodcra, a group of plant inhabiting nematodes 

 whose eggs will pass through the alimentary canal un- 

 altered. Figure 135F shows the egg of Heteroderu 

 marioni 'which is similar to those found by Kofoid and 

 White. These were extracted from worms occurring in 

 nodules of potatoes. ,^ We have encountered similar eggs 

 following gastric expression of a patient suffering chronic 

 stomach trouble. A lettuce sandwich had been eaten 

 shortly prior to the examination which was the cause 

 of the so-called "neniic infection." Though often asym- 

 metrical, the eggs of the Oxyuroidea may be oval as in 

 Oxjjuronema atdophora (Fig. 135K), spheroid as in 

 some of the Thelostomatidae as reported t)y Chitwood 

 (1932), or truncate as in Oxyuris equi. 



The degree of development at the time of deposition 

 shows considerable variation; Oxyuroncma atelophora eggs 

 are discharged in early segmentation stages, Enterobius 

 vermicularis, and others, are embryonated at the time 

 of discharge. 



Zawadowsky and Schalimov (1929) figure the egg of 

 Enterobitis vermicidaris as possessing a wide protein coat 

 extending far beyond the chitinous shell. The appearance 

 of the protoplasmic mass indicates that the egg figured 

 was derived from the ovarian portion of the uterus. In 

 all probability the "albuminous" coat had not condensed 

 as it would later. R«ardon (1938) shows the protein 

 coat in this species to be much thinner at the time of 

 oviposition, which is supported by our studies (Fig. 135M). 



AscARlDoiDEA. (R. O. C). The eggs of the ascaroid 

 worms have been studied by 'aiologists since the middle 

 of the past century. The classic work of Nelson (1852) 

 demonstrating the penetration of the egg by the sperm 

 and its subsequent development, and the cytological studies 

 of Boveri', (1888) have added muvh to our knowledge of 

 the phenomena associated with sex cells. During more 

 recent years studies on longevity, environmental factors 

 influencing development, and on the permeability of the 

 layers have been directed upon the eggs of this group. 

 Ascarid eggs have become to cytology and cellular 

 physiology what the frog is to general physiology and 

 morphology, an indispensible lat-jratory subject. 



In general the eggs of the Ascaridoidea are thick-shelled 

 and possessed of three membranes in the egg envelope, 

 namely: (1) the external protein coat which may be 

 mamniillated and deeply pigmented, giving a brown 

 color; (2) the chitinous shell which is thick and quite 

 ti-ansparent, and (3) the vitelline membrane which may 

 contain coarse reticulation of the periphery. The typical 

 shape is that of a regular ellipse but spherical or sub- 

 globular forms are well-known (Toxocara caiiis, Fig. 

 135AA). In some species the eggs are almost oblong 

 in outline (Ascaridia lineata. Fig. 135EE). Usually de- 

 velopment does not progress beyond early segmentation 

 stages in ntero, the eggs requiring relatively long periods 

 of incubation in the soil before they become embryonated. 



The protein coat of the ascaroid eggs is a thick layer 

 in some species and coarsely mammillated, for example, 

 Ascaris himbricoides (Fig. 135W). In other forms it is 

 thinner and marked by less prominent irregularities as 

 seen in Toxocara cants (Fig. 135AA). Baylis (1936) 

 describes the condition in Toxocara pteropodis as pitting 

 (Fig. 13.5Z). Parascaris equoi-mn has eggs in which the 

 mammillations are even less pronounced. Upon surface 

 view the exterior of the latter three species may give a 

 honey-comb appearance. Other eggs present a perfectly 

 smooth outline, the protein coat being barely discernible 

 about the margin of the thick shell. 



Variations occur in the appearance of the protein coat 

 in normal eggs, but they are especially noticeable in un- 

 fertilized eggs. Unfertilized eggs of Ascaris lumbricoides 

 have received much study because of their clinical im- 

 portance (Miura and Nishiuchi, 1902; Foster, 1914; Otto, 

 1932; Keller, 1933; Matuda, 1939, et. al). In some in- 

 stances the protein coat and the chitinous shell are 

 apparently lacking, the vitelline membrane alone cover- 

 ing the highly vacuolated protoplasmic mass. In others 

 the protein coat may be lacking, with the shell and the 

 vitelline membrane appearing to be perfectly normal. 

 In still other cases the protein coat may bo thickened 



and distorted to produce grotesque shapes. Blanchard 

 (1888) reports a stringy appearance in the mammillation 

 occurring at times in normal fertilized eggs of Ascaris 

 lumbricoides. This is thought to be due to the cohesion 

 of eggs entering the vaginal portion of the uterus. Fig. 

 135 LL shows some of the variations found in unfertilized 

 eggs of Ascaris lumbricoides as observed by Otto, 1932. 

 Matuda (1939) points out that an anomalous condition 

 is sometimes found in this species in which several egg- 

 cells are bound together by a single chitinous shell. 

 Stratification of the chitinous shell has been noted by 

 some authors. Nelson (1852) observed this in Toxocara 

 cnti, and it has been reported more recently by Zawadowsky 

 (1928) in several species of ascaroid worms. 



The vitelline membrane is relatively thick and, in some 

 species, filled with coarse reticulations. This is seen 

 most clearly in the eggs of Toxascaris Iconina (Fig. 

 135Y), but also occurs in Parascaris eqitorum (Fig. 136X). 

 The reticulations disappear following treatment with 

 ordinary fat solvents and are considered to be lipoidal in 

 nature. The vitelline membran«s in Toxocara can is and 

 Ascaridea lineata have a dense, granulated appearance 

 which may run toward reticulation. 



Opercula have been reported for some of the ascaroid 

 eggs. Dorman (1928) records two opercular plugs for 

 the eggs of Heterakis papillosa. These, he states, are 

 seen most prominently in the second membrane, but 

 usually extend through all three. The eggs of Heterakis 

 (jallinae possess no plug-like structures but a lenticular 

 clear space is present at one pole (Fig. 135CC). The 

 shell may be somewhat thickened in this area. 



Ackert (1931) presents a classic study on the morphol- 

 ogy and development of the eggs of Ascaridea lineata. 

 He states that the shells begin to form in the distal 

 portion of the uterus, and that they are composed of 

 three membranes: (1) an inner, highly permiable vitelline 

 membrane, (2) the thick, resistant shell, and (3) a thin, 

 "albuminous" covering. In one end a structure resembling 

 a micropyle was seen which on micromanipulation was 

 found to be a solid, conical appendage of the vitelline 

 membrane. Baylis (1929) considered this structure to 

 be an internal thickening of the shell. 



Aside from the structures already mentioned the shell 

 of Ascaridoidea eggs presents some additional modifica- 

 tions of interest. Olsen (1938) reports a thickening of 

 one side of the shell in Aplcctana gigantica.- This egg is 

 spherical, or subglobular in outline, and the thickening 

 is confined to the chitinous shell and does not involve 

 the other membranes (Fig. 135BB). 



In general the eggs of the Ascarididae and Heterakidae 

 require incubation outside the host before they are em- 

 bryonated. There are exceptions to this, however, as 

 in the case of Ascaris phacochoeris from the wart hog. 

 Ortlepp (1939) finds intra-uterine development of the 

 eggs to the embryonic stage in this species. Cosmocer- 

 cella haheri is an example of an ovoviviparous form. 



Dracunculoidea. R. O. C. But few observations have 

 been made upon the intra-uterine stages of the Dracun- 

 culoidea. Draciinculus nicdinensis, a commonly reported 

 viviparous species, is actually ovoviviparous since typical 

 eggs are formed in utero covered by a vitelline membrane, 

 a chitinous shell, and possibly a very thin protein coat 

 presenting a slight degree of rugosity (Fig. 141N). 

 Intra-uterine hatching occurs since the vaginal portion 

 of the uterus is filled with the characteristic, long-tailed 

 larvae. 



True viviparity may occur in this group in the case 

 of Micropleura vivipura. Baylis and Daubney (1922) 

 state that the development of the embryos appears to be 

 very rapid, the uterus being entirely filled, from end 

 to end, with young apparently fully formed and not 

 inclosed in membranes. Thomas (1929) similarly does 

 not mention the presence of eggs in Philometra nodulosa. 

 Van Cleave and Mueller (1934) likewise made no men- 

 tion of the eggs in the latter species. 



Spiruroidea. (R. O. C.) Little can be said regarding 

 the general chara:teristics of the egg-s of the superfamily 

 Spiruroidea. Usually they possess smooth, thick shells 

 and ars embryonated at the time of discharge. 

 The egg envelope is composed of the three typical mem- 

 branes; the protein coat, the chitinous true shell, and 

 the vitelline membrane. The general shape is that of 

 a regular ellipse, but various specialized shapes exist. 



183 



