senere i den Anledning anstillede noiere Under- 
sogelser har dog ikke forekommet mig overbevi- 
sende nok til at jeg tor fastholde denne Opfatning. 
Hoist merkverdig er Aiggenes lange Leve- 
dygtighed, der endog synes at hamle op med den 
vel bekjendte seige Spireevne hos lenge opbevarede 
Plantefro. Som ovenfor anfort, forsynede jeg mig 
Sommeren 1889 med et storre Qvantum af torret 
Mudder fra den Aaret iforveien af Prof. Collett 
undersogte Kulp ved Hamar. Af dette Mudder, som 
jeg har staaende i en liden Kasse paa mit Laboratorium 
i den Tilstand, hvori det blev taget, har jeg senere 
hver Sommer udtaget Smaaportioner og dermed. an- 
stillet Udklekningsforseg i mine Aqvarier. Disse Ud- 
klekningsforsog har endnu ikke nogen Gang slaaet 
feil. Altid har store Mengder af Larver inden meget 
kort Tid vist sig i Aqvarierne, og af disse Larver 
har i Regelen ialfald en Del gjennemgaaet sin hele 
Udvikling. De paa denne Maade kunstigt opdret- 
tede Individer har jeg havt gaaende i mine Aqva- 
rier mere eller mindre langt ud overSommeren. De 
har tilsyneladende trivets udmerket, har paa sed- 
vanlig Vis produceret sine Aigpaketter og har ial- 
mindelighed naaet den samme Maximumsstorrelse 
som de af mig frit indsamlede Exemplarer. Ved de 
forste Forsog udklekkedes sammen med Limnadierne 
ogsaa forskjellige andre Entomostraceer; men i de 
senere Aar er det alene Limnadier, der lader sig 
udklekke af Mudret. Ganske nylig har jeg i et 
opvarmet Rum gjort et nyt Forsog med det samme 
Mudder, og ogsaa denne Gang, altsaa fulde 6 Aar 
efterat Mudret blev taget, ser jeg, at Larver ud- 
klekkes i temmelig betydeligt Antal, trods den 
uheldige Aarstid (vi skriver idag, da dette ned- 
skrives, den 18de Februar). Det er min Agt at 
fortseette Experimenterne fremdeles med den tilovers- 
blevne Rest af Muddret, da det forekommer mig at 
have adskillig Interesse at faa paa denne Maade 
sikkert constateret Udstrekningen af Auggenes Leve- 
dygtighed. En ganske besynderlig Omstendighed 
maa jeg her neyne, og det er, at det endnu ikke 
har lykkets mig at faa de i mine Aqvarier afsatte 
Mg af denne Form udklekkede, skjondt Residuet 
er behandlet paa samme Maade som ved andre Ud- 
klekningsforsog, idet jeg har ladet det ligge i ind- 
torret Tilstand Vinteren over. Det synes herefter 
nesten som om Aggene af Limnadia trenger, for 
at kunne udvikle sig, at ligge torre ikke blot et, 
men flere Aar itrek. At jeg paa Merdo har paa- 
truffet denne Phyllopode i 2 paafolgende Aar paa 
de samme Lokaliteter, kan ikke egentlig siges at 
modbevise en saadan Hypothese, da det jo aldeles 
ikke er afgjort, at de paatrufne Individer netop 
er udklekkede af de den foregaaende Sommer af- 
satte Ag. 
De eiendommelige vingeformige Udvidninger, 
114 
but the results of more careful observations made 
by me subsequently, have not appeared to me to 
be sufficiently convincing to permit of my main- 
taining that view. 
The great vitality of the eggs is most remar- 
kable, and seems to be on a par with the well-known 
tenacious germinating power in long preserved plant 
seeds. As already stated, I provided myself, in the 
summer of 1889, with a considerable quantity of dried 
mud from the pool near Hamar, examined by Prof. 
Collett the year before. Of this mud, which stands’ 
in a little box in my laboratory, in the condition 
in which it was taken, I have since then, every sum- 
mer, taken out small quantities, and made hatching- 
experiments in my aquaria. These experiments 
have never yet been unsuccessful. Always, within a 
very short period of time, large numbers of larvee 
have made their appearance in the aquaria, and, as 
a rule, a proportion, at any rate, of these larve 
have gone through their whole development. The 
specimens artificially reared in this way have lived 
in my aquaria more or less far on towards the end 
of the summer. They have apparently thriven well, 
have produced their egg-masses, and have generally 
attained the same maximum size as the naturally- 
reared specimens collected by me. At the first 
attempts, various other Entomostraca were hatched 
with the Limnadie; but in the later years, 
Limnadie only have been hatched from the mud. 
I have quite recently made a fresh trial with the 
same mud in a heated room; and this time too, 
fully six years after the mud was taken, I see 
that the larve are being hatched in considerable 
numbers, in spite of the disadvantageous time of 
year (it is the 18th February when I write this). 
It is my intention to continue the experiments with 
the remainder of the mud, as it appears of conside- 
rable interest to me to prove with certainty in this 
way the extent of the period of the eggs’ vitality. 
One very peculiar circumstance I must mention 
here, namely, that I have not yet succeeded in 
hatching out any of the eggs deposited in my 
aquaria by this form, although the residuum has 
been treated in exactly the same way as in other 
hatching experiments, as I have left it in a dried-up 
condition throughout the winter. It seems from this 
as if the eggs of Limnadia, in order to be able to 
develope, require to lie dry, not one year only, but 
several years in succession. The fact that on Merdo 
I have met with this Phyllopod in the same loca- 
lities 2 years in succession, cannot really be said 
to disprove such a hypothesis, as it is not at all cer- 
tain that the specimens found were hatched from 
eggs deposited the previous summer. 
’ 
The peculiar wing-like expansions with which the 
