1897] NOTES AND COMMENTS 369 



above the average, and thus many Queens were early tempted from 

 their winter quarters. Turning now to the numbers of wasps 

 observed — in spring there were many ' Queens ' to be seen, and 

 many persons observed to me that we might expect a recurrence of 

 the ' plague ' of 1893. This prediction was entirely falsified, for in 

 all parts of the country wasps were conspicuously absent during 

 August and September. My own observations on this point were 

 conducted in Surrey, Hampshire, Norfolk, Hertfordshire, and Kent, 

 and I am informed by friends that the same was noticeable in Scot- 

 land, Lancashire, and Somersetshire. These facts seem to me 

 sufficiently conclusive of the truth of my former conclusion, and I 

 should esteem it a favour to be allowed to invite information from 

 any of your readers whose experience may perhaps, during the past 

 year, have furnished further evidence in the same or the opposite 

 direction." 



Models of Cells 



Prof. A. L. Herrera has recently published in the Memorias y 

 Eevista dc la Sociedad Cicntifica 'Antonio Alzate,' Mexico, 1897, 

 two interesting essays, in which he describes some attempts of his 

 to make working models of the impact of forces upon cells and 

 protoplasm. He points out that in the part of physiology dealing 

 with the elaborate mechanisms of higher animals the construction 

 of models, such as those to illustrate the flight of insects or the 

 action of the valves of the heart, has been useful ; and he attempts 

 to apply the same principle to the fundamental phenomena of 

 protoplasm. To a certain extent he has been anticipated by 

 Butschli and others, and we are bound to admit that his working 

 models are of coarser texture and apparently less adapted to the 

 delicate reaction of protoplasm than the oil foams of his predeces- 

 sors. None the less, many of his experiments are interesting and 

 ingenious, and may serve a useful purpose in kindergarten science. 

 In the first essay, entitled ' Los Infusorios Artificiales,' he tries to 

 explain vibratile movements of cilia by means of elastic tubes con- 

 taining diffusible liquids and placed in other liquids. His idea 

 appears to be that osmosis currents between protoplasm and water 

 and the stresses produced in the elastic cell-wall set up the vibra- 

 tions. In the second essay, written in French, he describes a series 

 of experiments showing the reaction of elastic spherical bodies to 

 pressure by the elastic surfaces. He obtained a number of results 

 strikingly resembling known animal and plant forms. We com- 

 mend his essays to the curious. 



