THE SAKCODINA 235 



Schaudinn (131) ; their results have been confirmed in the case of 

 Peneroplis by Winter, who gives a useful combined diagram of the 

 life -history (28, p. 16, text -fig. A). The microspheric form 

 (Fig. 95, jB.) has many nuclei, which multiply by fission as the 

 animal grows, and which also give off chromidia into the body- 

 protoplasm. When reproduction begins, the nuclei become resolved 

 entirely into chromidia, and the protoplasm streams out of the 

 shell, which is abandoned altogether. Secondary nuclei are formed 

 from the chromidia, and the protoplasmic mass divides up into a 

 swarm of about 200 amoebulae (Fig. 96). Each amoebula contains 

 a nucleus and chromidia, and secretes a single-chambered shell, 

 which is the initial chamber of a megalospheric individual. The 

 amcebulse separate, ar d each one feeds, grows, forms new chambers 

 successively, and becomes a megalospheric adult. Thus the micro- 

 spheric form is seen to be an agamont or schizont, which gives rise 

 by a process of schizogony or multiple fission to agametes (amoe- 

 bulae). The megaiospheric form, when full grown, has a single 

 large nucleus and numerous chromidia (Fig. 95, A). The nucleus 

 is that of the amosbula which was the initial stage in the develop- 

 ment of this form ; as it grows the nucleus passes from chamber *o 

 chamber, and at the same time gives off chromidia into the cyto- 

 plasm. Finally the primary nucleus is resolved entirely into 

 chromidia, from which a great number of secondary nuclei are 

 formed. Round each such nucleus the protoplasm becomes con- 

 centrated to form a small cell, which may be termed a gameto- 

 cyte. By two divisions of the nucleus and cell -body of the 

 gametocyte four gametes are formed, each of which acquires two 

 flagella, and is set free as a biflagellate swarm-spore. In Pener&plis, 

 however, the gametes have a single flagellum, and in Attogromia 

 ovoidea the gametes are amoebulae (Swarczewsky). Gametes pro- 

 duced by different individuals copulate, losing their flagella in the 

 process, and the zygote secretes a minute single-chambered shell, 

 and thus becomes the starting-point of the growth of a micro- 

 spheric individual. 



From the foregoing it is seen that the megalospheric form is the gamont, 

 which by multiple fission produces the gametocytes, and ultimately the 

 gametes. Thus, if m. represents the microspheric form and M . the megalo- 

 spheric, am. the amoebulae (agametes), and fi. the flagellulse (gametes), the 

 life-cycle may be represented thus : 



m. am. M. (fl. + fi.) m. am. . . . 



In some cases, however, the life -cycle does not present a regular alternation 

 of sexual and non-sexual generations, but a number of non-sexual generations 

 may take place before a sexual generation intervenes ; that is to say, the 

 megalospheric forms may produce agametes and other megalospheric forms 

 again for several generations, before gametes are produced and the sexual 

 processes occur. Then the life-cycle may be represented thus : 



m. am. M. am. M. am. . . . M. (fl.+fi.) m. am- M. . . . 



