THE 



MONTHLY MICROSCOPICAL JOURNAL. 



DECEMBER 1, 1874. 



I. — Continued Besearches into the Life History of the Monads. 

 By W. H. Dallinger, F.Pt.M.S., and J. Drysdale, M.D., 

 F.E.M.S. 



(Read before the Royal Microscopical Society, Nov. 4, 1874.) 

 Plates LXXXIII., LXXXIV., and LXXXV. 



The prosecution of our inquiries as to the developmental history 

 of the minute monad-forms found in macerations of fish was con- 

 tinued during the past summer. Our methods were precisely the 

 same as those previously described ; so also was our mode of work, 

 everything being mutually accepted as a correct interpretation. 

 Prolonged work with infusions has led us to make observations 



DESCRIPTION OF PLATES LXXXIII., LXXXIV., AND LXXXV. 



Fig. 1. — Typical specimen of the monad described. 

 „ 2. — Shows the different positions taken by the enlarged bases of the flagella 



when the latter are in motion. 

 „ 3. — The peculiar structure a, b, intimately connected with the bases of the 



flagella c, indicates a probable organ of locomotion ; of which b may 



be muscular. 

 „ 4. — The earliest condition of change of state, showing hyaline investment 



more clearly. 

 „ 5. — First constriction within the hyaline. 

 „ 6. — Constriction more developed. 

 „ 7. — The first division into two complete; but the forms are still within 



the hyaline. 

 „ 8. — 'R'ansverse constriction ensues in each of the preceding. 

 „ 9. — Division into four has taken place, and the flagella of some of the 



enclosed ones are protruding. 

 „ 10. — Further multiplication has ensued, and the first of the new forms is 



escaping from the hyaline investment. 

 „ 11. — The hyaline enveloiae after all have escaped. 

 „ 12. — The same when one or more has aborted. 

 „ 13. — A specimen of the granular form from which parthenogenetic elements 



are emitted. 

 „ 14 and 15. — The emission of the above. 

 „ 16, 17, and 18. — The condition of the monad after emission. 

 „ 19 and 20. — The germinal points seen in the granules of sarcode emitted, as 



discovered in the process of development, x 10,000 diam. 

 „ 21. — Sexual contact. 

 „ 22. — The earliest result of the blending. 

 „ 23. — The still condition which follows. 



„ 24 and 25.— The cyst bursting and emitting a cloudy mass containing germs. 

 „ 26 and 27. — Represent the " clubbed " condition. 



VOL. XII. U 



