40 



HARDWICKE'S SCIENCE -GOSSIP. 



b eauty and accuracy of the figures. Herr Schmidt 

 states that he has prepared 9,000 figures drawn to the 

 s cale of 900 diameters, from which selections will be 

 made for the atlas, preferably of those genera which 

 require careful illustration; at the same time new 

 forms will be introduced, and where possible placed 

 in juxtaposition with those species to which they 

 bear the greatest affinity.* — F. K. 



Researches in the Life History of Monads. 

 — We wish particularly to call the attention of those 

 of our readers who are interested in these minute 

 forms, to a paper bearing the above title, and read 

 before theRoyal Microscopical Society.f The authors, 

 Messrs. Dallinger and Drysdale, after a reference 

 to their previous papers on this subject, proceed 

 to describe how the forms investigated were ob- 

 tained ; viz., by the maceration of the heads of cod- 

 fish and salmon for several months. A circumstance 

 of considerable interest occurred in connection with 

 these experiments. The authors say," We always work 

 from a small quantity of the large vessel of decaying 

 matter which we keep at hand. During the early 

 summer the intense and continued heat evaporated 

 all the fluid from the salmon's head infusion with, 

 out our knowledge. The form we were working had 

 been in great profusion. It was growing less 

 abundant in our small washing-tanks, and we feared 

 we must wait another year to finish our inquiry. 

 But we led a forlorn hope, and took the hard, 

 porous, dried papier-mache-like mass which formed 

 the dried residuum of the infusion, and determined to 

 put it in an exhausted maceration of the same kind, 

 which at that time showed only very feeble signs of 

 any life, and certainly no monads. We watched the 

 result, and to our great surprise in three days the 

 required monad appeared in remarkable vigour, and 

 daily increasing abundance, enabling us to complete 

 our researches into its cycle of development." In 

 addition to this, another and remarkable form made 

 its appearance, whose history the authors were en- 

 abled to complete, and which had very feebly shown 

 itself previous to the drying up of the infusion, but 

 now showed great vigour, and eventually survived and 

 predominated, evidently very much at the expense 

 of other forms. This new form possessed more 

 distinctive and distinguishable structure than any 

 other so low in the scale of life with which the 

 authors were acquainted. This form they thus 

 describe :— "The sarcode is invested with a distinct 

 hyaline envelope perfectly structureless to our best 

 appliances, and sharply distinguished from the pro- 

 toplasm of the body; two flagella, inserted into 

 what appears like a special organ of locomotion ; a 

 large central disc or nucleus-like body ; numerous 

 protoplasmic granules ; a pair of " snapping " eye- 



* Subscribers* names will be received by the publisher of 

 this Journal. 



t Published in No. 72 of the Monthly Microscopical Journal. 



spots, and occasionally some remarkable club-like 

 appendages to the anterior of the'body, the nature 

 of which we have failed to ascertain." The shape of 

 these remarkable organisms appears to be oval, and 

 the size (exclusive of the flagella) when magnified 

 1,300 diameters, is It inch the long diameter, and 

 1 inch the short diameter; the flagella are about 

 twice the length of the body. By continuous 

 observation on the normal form, with a power of 

 1,200 to 10,000 diameters, they were able to trace 

 the cycle of change. In about 40 minutes a line 

 across the short diameter appeared, and soon after 

 a marked constriction within the hyaline membrane 

 might be detected, the motion of the monad the 

 whole while remaining unaffected. In about two 

 hours from the first a total division take6 place, 

 the hyaline membrane still remaining intact. After 

 swimming freely for not less than 10 minutes, an 

 indentation may be observed in the long axes of the 

 divided bodies ; and in from 7 to 20 minutes a con- 

 striction longwise ensues. After this the divided 

 bodies remain within the hyaline envelope, some- 

 times dividing into 8 and even into 16, and swim- 

 ming about with an elegance and ease not sur- 

 passed by Folvox globator. After swimming in 

 this way for from 10 to 100 minutes, one of the 

 forms escapes, and becomes a perfect monad like 

 its parent. This method of increase goes on with 

 great rapidity, and for many generations. For a 

 detailed description of other modes of increase, we 

 must refer our readers to the lucid and minute 

 descriptions of the authors ; and we think that the 

 unprejudiced reader will come to the conclusion 

 that these experiments are fatal to the theory of 

 spontaneous generation. We find that germs are so 

 minute that the highest powers of the microscope 

 are unable to detect anything but a filmy cloud, 

 and that only after some hours' patient observation 

 can the first rudiments of an organism be detected. 

 The authors have also proved that ordinary desicca- 

 tion, or even heating up to 250° Fahrenheit, does not 

 destroy their vitality. 



Mounting Selected Diatoms.— I have at 

 various times received from my friend Herr Weiss- 

 flog, slides of selected diatoms (not arranged in 

 patterns, the doing of which is a shameful waste of 

 time), mounted in a manner which leaves nothing to 

 be desired. The forms are mounted on a thin 

 cover, § of an inch in diameter ; a thin silver disc of 

 similar size, with a central perforation, sometimes as 

 small as the 3 y, of an inch in diameter, is then mounted 

 on the slide, and the glass cover placed upon it, and 

 pressed down, the central aperture of the disc form- 

 ing a tiny cell for the diatoms. Two advantages 

 arise from this method of mounting ; viz., the ease 

 with which an object is found, and the cutting off a 

 considerable amount of extraneous light. A further 

 recommendation is the very neat appearance of the 

 slides.— F. K. 



